I recently but a Guf windshield on my Cross Country. I would not worry about paying the extra for acrylic bits, especially if you own a dremel tool.
Here's the way I did my install:
Place the windshield on the bike in the position you plan to mount it. Use a sharpie marker to mark the centers of the holes for the mount screws. When marking your holes, make sure you have the windshield pressed down against the frame as much as possible.
Use a brand new 1/8" drill bit to SLOWLY drill your holes through the windshield. Do not push the drill though the windshield as this can cause the drill to grab too much plastic as it's cutting through, resulting in chipping. Let the drill slowly remove the plastic as it cuts through the windshield, using no more force than the weight of the electric drill itself.
Once the holes are drilled, use a tapered grinding stone on your dremel tool to slowly enlarge the drilled holes until you have removed enough plastic to allow the screws to go through, plus a little extra for free play. The object here is to create holes for your screws that show no signs of any fractures or burrs in the plastic as this is where cracks would most likely develop.
Once your holes have been enlarged to accomodate the screws, install your windshield taking special care not to over tighten the screws. Just make them tight enough to hold the windshield securely in place and you're done.
Hope this helps.