Yes -- the Sun-Mar Excel model can be installed practically anywhere. It simply requires a vent stack and a 110v electrical outlet within six feet of the toilet.
The waste material enters into a Bio-Drum (TM) directly beneath the toilet seat. Since the waste falls straight down into the drum, water is not necessary. Water is typically used in conventional sewage systems to move things from place to place -- with the Excel, the waste is exactly where it needs to be to be treated upon entering the Bio-Drum - so no water is necessary.
Other products that would be great for the application "basement toilet" are listed below.
In the Bio-Drum, in combination with a bulking material (Compost Sure) the waste is composted into soil by aerobic bacteria and the soil is removed approximately once a month (residential use) or once a year (seasonal use).

Yes -- The Sun-Mar Excel toilet is rated for 4 people for continuous use. In terms of actual toilet "uses" this comes down to 6 bowel movements and 30 urinations per day. The people working within the shop will no doubt use the toilet multiple times per day, whereas the visiting customers will likely spend a shorter portion of the day in the shop and will likely use the toilet one time, if at all. If higher urine input is expected (as it may be in this case) then Sun-Mar recommends connecting the drain for liquid overflow (see photo below) and running it to an appropriate disposal area (e.g. sanitary drain, septic, holding tank or leaching pit). The toilet will generally evaporate all the incoming urine out of the venting stack, but in the instance of a power outage, or uncommonly high urine input, the drain would safely and cleanly eliminate the excess.

First and foremost, all Sun-Mar toilets are very sturdy in their construction and will endure cold temperatures without problems.

Limited Use in winter

For limited use (i.e. only a couple of weekends a month at most) in cold temperatures, the unit can be used simply as a holding tank as composting will NOT occur below 13 Degrees centigrade. For this, sufficient space must be available in the Bio-drum and the drum should not be rotated if it contains frozen compost. Electric units should be plugged in when in use, so that the fan eliminates all odors even though no composting is taking place. If you have an Excel-NE (Non-Electric), you should install a 12 Volt fan to assist airflow during use in the winter months.

This advice is applicable to all planning on using the unit once a month or so in winter. If you are planning on using the unit more frequently during the winter months, please follow the advice in the section below.

Extended Winter Use

For continuous or extended use in winter (i.e. every weekend, or residential use), the composting unit will have to be kept warm (at least 55°-60° F/ 14°C) so the composting activity does not stop.

Insulate all piping in unheated areas to avoid ice blockage including vent stacks (on all units). While the composting unit is not in use, energy costs can be reduced by installing a speed control on the fan so that very little cold air is being pulled in and the heater is operating less frequently. This speed control is available from our parts department.
Keep self-contained electric units plugged in if they are in a cold place. If a self-contained unit is being operated in an unheated space, consider putting a blanket over the unit to keep the unit insulated and further reduce heating costs. Please note that this will not be enough to bring the unit up to a proper composting temperature.
If you are planning on installing a unit in a climate with extreme temperatures (e.g. Saskatchewan / Northern Canada), consider installing a 3" pipe around the insulated 2" pipe to add an extra measure of installation. Many of our customers in these areas also use heat tape or self-regulated heat cable along the length of the vent to keep ice from blocking the vent in the winter months. Contact Sun-Mar representatives for additional advice if planning to install a unit under these circumstances.

The Excel vent pipe is 2" diameter and may be run through the ceiling or the wall. For "best practice" venting recommendations please read through the following:

1) If running a vent through a wall, it should be done at a 45° angle to prevent condensation from accumulating in the vent pipe, causing a constriction. THERE SHOULD BE NO HORIZONTAL SECTIONS OF VENT. Venting should be installed vertically wherever possible.

2) All vent pipe that is exposed to the outside or in a non-heated space should be insulated if using the unit during cold weather.

3) INSTALL VENT SO THAT IT TERMINATES 24” - 30” ABOVE HIGHEST PEAK OF THE ROOF.

4) If you will be installing venting on a steeply pitched roof where snow shear may occur; Install a heavier pipe through the roof and feed the enclosed vent through the heavier pipe. Seal between the pipes with expandable foam or other such water-tight substance. The heavier pipe should be able to withstand the weight of sliding snow.

5) If there is more than 36” of vent needed above the roof line to reach 24-30” above the highest peak of the roof (diffusor included in measurement), use guy wires to secure the vent above the roof.

6) Limit bends in the vent stack to no more than 4 that have a combined total of 180 °.

7) The vent must be installed separately from ALL other household vents. Venting cannot be merged with other venting. Doing so will prevent the unit from operating odorlessly.

8) All connectors in the vent pipe should be sealed. Use silicone caulking to seal the connection between the vent and the fan. PVC cement may be used all other vent connections.

9) The diffusor should be glued vertically on to the top of the vent pipe. This assembly helps draw air up the vent pipe.

Where 110v grid-tied electricity is available, electric units when used, are equipped with a 25 watt fan for ventilation and a 260 watt, thermostatically-controlled heater for liquid evaporation (urine). These toilets, because they are waterless units can typically evaporate all the liquid. There may be some scenarios where there may be too much liquid (e.g. a party with much alcohol consumption) where liquid input may "outpace" evaporation from the toilet and in this case (or during power outages), an "emergency drain" for liquid is recommended. This can be connected with a hose to a container.

The Excel non-electric model is ideal for installation where electricity is NOT available, or where generators are being used, or alternative power (DC from solar power). These units will not evaporate liquid and must have the drain connected.

To summarize, the electric Excel will evaporate liquid and the non-electric Excel will not.

Sun-Mar units serve as a reliable year-round facility when prepared for continuous or periodic use during the cold winter months. All units are made of fiberglass and marine grade stainless steel; so even if the compost freezes in the drum, sub-zero temperatures will cause no damage.

Limited Use

For limited use (i.e. only a couple of weekends a month at most) in cold temperatures, the unit can be used simply as a holding tank. For this, sufficient space must be available in the Bio-drum and the drum should not be rotated if it contains frozen compost. Electric units should be plugged in when in use, so that the fan eliminates all odors even though no composting is taking place. If you have an Excel-NE or an AC/DC that you are using primarily in DC mode, you should install a 12 Volt fan to assist airflow during use in the winter months.

This advice is applicable to all planning on using the unit once a month or so in winter. If you are planning on using the unit more frequently during the winter months, please follow the advice in the section below.

Extended Winter Use

For continuous or extended use in winter (i.e. every weekend, or residential use), the composting unit will have to be kept warm (at least 55°-60° F) so the composting activity does not stop.

Insulate all piping in unheated areas to avoid ice blockage including vent stacks (on all units), and waste inlet and drain piping where appropriate.
While the composting unit is not in use, energy costs can be reduced by installing a speed control on the fan so that very little cold air is being pulled in and the heater is operating less frequently. This speed control is available on a special order basis.
Keep self-contained electric units plugged in if they are in a cold place. If a self-contained unit is being operated in an unheated space, consider putting a blanket over the unit to keep the unit insulated and further reduce heating costs. Please note that this will not be enough to bring the unit up to a proper composting temperature.
If you are planning on installing a unit in a climate with extreme temperatures (ie Alaska or Northern Canada), consider installing a 3" pipe around the insulated 2" pipe to add an extra measure of installation. Many of our customers in these areas also use heat tape or self-regulated heat cable along the length of the vent to keep ice from blocking the vent in the winter months.