The method of drilling holes in glass plates is to take an old twist drill, see that it is properly sharpened, and harden it by beating the point to a cherry red over a gas flame, and quench in ordinary soldering "acid," that is, chloride of zinc solution. Use this drill in the ordinary way in a bit brace or hand drill, lubricating the point with turpentine. A quarter-inch hole is very easily made in this way. Then take a medium coarse rat-tail file, moistened with turpentine, and the hole may be enlarge to required size in a few minutes. Care should be taken not to get the file stuck in the hole while it is still small.
Try this on a waste piece of glass first. If the drill gets dull it must be ground and then hardened again.