Phillip,
I think the AS130MM camera uses WDM when you use it with phd so you shouldn't need ascom drivers. You can download phd and get the camera working without the GPUSB but will need it to get the guide signals to the mount if you want to use the ST4 guide interface. If you are using eqmod you don't need a GPUSB - you can use pulse guiding through eqmod.
http://eq-mod.sourceforge.net/tutindex.html
Check out the guiding bit under documentation.
Peter