I have used water jet cutting to drill holes into glass. It works very well on non tempered glass.
On Tempered glass drilling a hole is a bad thing. I had a try at it just as well and while it seemed to have worked initially, the samples cracked after a while due to slow crack formation.
One more advantage with water jet cutting is that you can freely chose the shape of your hole (might not be of any use to you in this case).
you casually find a business with a water jet cutter in a industrial park.
"It is neither wealth nor splendor, but tranquility and occupation which give happiness." -- Thomas Jefferson