Did your Goggle search take you to the recently posted question here on shower timers?
http://www.askmehelpdesk.com/cgi-bin...num=1087096830
In that answer Tom suggested adapting a timer meant for lawn sprinkling to a shower. I think it would mean removing the short, bent pipe usually coming out of the wall and installing the timer ahead of it. I think the thread next to the shower head is a special thread that may not fit anything except shower heads.
I didn't think I could add anything, so did not answer that question. If you need more details on the plumbing, post back and Tom or I will help you.
This sounds like it should work. More and more technology is available for those needing it. I am more aware of devices to aid the visually impaired, but learning more about other needs.
I am heavilly involved with service dogs, and am not sure where to find out about other technology.