Gidday all. Antman in Aussie land here. Had my right foot crushed 3 years ago. Doesnt work any more from the shin down. Walk with a stick now,permenant foot splint. Have had exellent help from MAP members in my searh for styles to help me out.
There's a really good article up on the web (in most search engines when you look up 'disability martial arts) about wheelchair techniques. Also when I was in USA a couple of years back I attended an excellent event near LA specifically for disabled people and they (a) put on a demo of wheelchair freestyle which was really good and (b) they had a company there promoting a special type of wheelchair with martial arts in mind.