Have a look at Antares tube rotators
http://www.scopestuff.com/ss_arrs.htm
I have put in an initial order, but haven't heard anything for more than a month. Antares are just starting production so they custom make each one. They are not cheap, but it is easier to buy a finished article some times than to try to develop something yourself.
I think they also have a high "cool" factor, especially for those who know of the problems with EQ mounts!