Very interesting project!
Did you consider interfacing CCD chip (TC237 in particular) to Arduino, so the sketch can guide the mount via ST-4 interface (OnSTEP, for example), completely stand-alone?
Some time ago I did something similar (it was for another application, with one of Philips processors), there was also very primitive "star" detection (assumed round illuminated shape, treshold was at 50% level from CCD chip), it sort of worked..)