I posted some pics of my drilling in the tank journal area under mmm...230.
BUT, here's a link to a video :
http://www.youtube.com/watch?v=F9MaQw1OsN8
The video I learned from seems to be missing, but that one is good.
Tape up the inside of the tank with duct tape where the hole will be, this will keep the glass from falling and I find it helps prevent chipping at the end.
Cheers.