[Okiesnake]

I would recommend first making a "X" with a razor blade through the outside vinyl at the center point of where you want the hole. Then make a small pilot hole from the front side of the dash. Next make several more cuts through the vinyl from the outer diameter of where the final hole is going to be towards the center of the circle. My drill bit of choice when making holes through fiberglass is one of those cone shaped bits that can cut bigger and bigger holes the deeper you drill. They are a little expensive but are the perfect tool for the job. A Dremel with a small drum sander also works well to slightly enlarge a hole.
Remember to pull back the pie shaped wedges in the vinyl when drilling. When you are done you can push the wedges through the hole when installing the starter button and not worry about the vinyl ever pulling away from the hole.