You should revise your 100% disabled statement, to be more clear. That's like saying you're completely immobile, and can't see, hear or speak. Clearly, you have sight and can (at the minimum) operate your head, arms and legs to some degree. Not trying to be a dick, but it seems you are still blessed with many abilities - not 100% disabled.
That being said, ideally you're going to have to be able to step into the SS with one leg, while supporting your weight with the other leg on the pavement. Not ideally, you could probably sit on the side and rotate legs inside, but then strong arms will need to compensate. While inside, you'll need clutch, brake and fuel pedal ability. Getting out I think you'll need to bring your legs up against the seat and kinda stand up, then swing a leg out over the side and reach the pavement.
If your legs are really the problem, and you don't always travel with someone who could hoist you in and out, I'm thinking the SS may be a hell of a challenge, even if you had a new automatic transmission and hand controls installed.