If the switches are normally open, then it is relatively easy to modify the handcontroller to control the scope. This document:
http://store.shoestringastronomy.com/do ... idance.pdfdescribes how to add relays in parallel with the switches.
Keep in mind, this will only do the same types of movements that the handcontroller itself would do. So, if the handcontroller only provides small, slow movement of the scope, this is all you will be able to achieve with the computer control. Also, there is no way to feedback the position that the scope is pointed to with this method. If you are looking for a way to make a complete GOTO mount, this will not work.