A while back I decided to have a go at building a cheap stepper motor controller & writing an ASCOM driver to allow it to control a focus motor. As it came to pass, I ended up getting a robofocus unit which is working well but I still managed to follow through with my DIY parallel port focuser as well. Whilst I never hooked it up to my focuser, I did get it all going "on the bench".
Perhaps someone it trying something similar, in which case this may help give them a head start. It comes with no guarantee that it's 100%. I'm sure that there are a few bugs in there but the basics seems to work.
Anyway, after much looking around for appropriate motors & controllers, I figured the easiest way to start was to go with a off-the-shelf product. I decided on the KV3594 stepper motor / controller kit from Jaycar
http://www.jaycar.com.au/productView...r&form=KEYWORD
I then set about writing an ASCOM driver to controll this specific kit. I ended up writing an ASCOM V5 driver (in VB.net). It can be downloaded from the following link
http://astroromp.com/astronomy/stepp...or_control.htm
Please note that this link contains both the source & executable files (ie, the ASCOM installer).
Good luck
Matt