Dennis:
Maybe not foolproof but darn close. Usually done between centers on a lathe with the blank being either held by hand (recommended)or fixtured against the compound. I drill from both ends. The drill is the important part. Most custom makers will use what's commonly known as a gundrill, easily shop made. (If nobody else chimes in with a picture of one I will take a photo of mine later today and post it.) It's a fairly slow process because you need to frequently clear the chips from the flute, but the drill will not wander. I have drilled dozens of holes and they normally will meet in the center within .020 or so.
Craig Libhart
