The PCs use their WP score for a Psionic WS, their Int for their mental S, and their Cl for their T, with wound taken in Insanity Points! They also got a # of A for every full 20 pts of Int. Then you run it like a normal combat. Because they are not proficient they get a -20 WP "WS". I let PC's with spell casting ability fight at a full "WS"
It might seem a bit hokey but, for my group, it add some variety and some character developing Disorders.:-). And this system could be developed further with skills and a career class, I have just used it for a dervision.
Thank you for your time.
From: "John N. Sweet" (email@example.com)
Date: Fri Jun 16 20:28:00 CDT 1995