You can find the list of physicians released in the Providence Journal a year or so ago.
I made an appointment with one on the list. Developed a relationship over some appointments to ensure my medical issues were valid and documented then took the next step and asked if it could be an option in my treatment. From what I understand it's taken very seriously right now and if you don't suffer from any approved conditions you would pretty much be turned down.
I hear your best bet might just be to appeal to your general practitioner, they usually know you best.