Dispensing foam soap requires a special pump. You can easily refill a foam soap container with a dilution of regular liquid soap to create a cheap refill of foam soap, but you have to have the special pump. If you can get the pump mechanism to fit on your built in dispenser then you are good to go.

Where can I buy a pump mechanism? I've only seen the complete unit--pump and bottle.

If anyone can figure out how to do this, I would love to know. Better yet, would there be a way to set it up with the Never-MT? My child has OCD tendencies and excessive handwashing is part of it. I have found that, by replacing the soap with foaming soap, it has eliminated the dry, red, bleeding hands that resulted from too frequent handwashing. I would love to put in new counter top's in the kids' bathroom, including undermount sinks and soap dispensers, but I hesitate because of the OCD issue.

Buy the foaming soap and dispenser ... swap tops, or swap innards to move the foaming part over.

I think it also requires thinner soap.