a mate of mine runs a company specialising in building these cars, custom set ups for the specific customer. i believe a majority of the cars produced are heavily modified kangoo's, but i think they can adapt most cars to suit.

http://www.sirusautomotive.co.uk

might be worth a look or a call for some advice etc. notice theres some info on there for converting manual gear systems also, using push button clutch to eliminate the pedal

and iv had a play in a hand control kangoo, the only issue at 1st is learning how much pressure to apply to the controls, and convincing ur hands to do the moving and not your feet, so more of a re-learning process, nothing impossible, and nothing that would take a lifetime to learn

they also build some awesome electric wheelchairs to go along with the particular cars, the best 1 being the recaro set up, with full movement, plus its fast as hell around the industrial estate