A while back I took opportunity to hack together a piece of Assistive Technology (AT) for a good friend of mine using a damaged pair of Apple Earphones with Remote and Mic. The first version, pictured on the right, is constructed with a three button array found on ebay.
The second version, pictured at the bottom, is constructed with large arcade buttons from Sparkfun and a custom enclosure that I made with sheet metal, a breaker bar and pop (blind) rivets. This version should be easier to use than the first as it has larger softer buttons, less dangling wires and a case that can withstand being squished between an electric wheel chair and a door frame.
If you are interested in what is inside the Apple Earphone controller, there is a wonderful tear down post.