Here's another link: Adaptive Equipment

I just discovered it and haven't had a chance to really look at the devices. The first one seems closer to what you meant than the rock-it barre.

Of course, I'm sorry about your disability, but this is a topic of great interest to me. I think there are many possibilities for making it possible for people with disabilities to play instruments.

I once had an interview at Otto Bock, which is a manufacturer of prosthetic devices near to the town where I live. "Near" is relative in this case, because Duderstadt, Germany, is in the middle of nowhere and a very strange place to put a factory. Unfortunately, I didn't get the job but I later heard that the working atmosphere there isn't too great.

One of the recorder manufacturers in Germany, either Mollenhauer or Moeck, offers lots of optional key systems for their recorders which make it possible to even play the recorder with one hand. Of course, recorders sound best when the air flow is blocked, but they haven't solved that problem yet.

I would think that it would be possible to play with two fingers, though not chords, of course. It could still be good.

A lap steel would also be an alternative, if the idea of a pedal-steel doesn't appeal or isn't possible for some reason.