Just build a ring around it with plumbers putty that's about 6" around then fill it with water.
No need for anything but water.
Put any type of tape on the underside as well as a towel on the panel at the opposite end so if you happen to go through the tape as well and it falls it won't break the tank. Start with the drill at a slight angle and once you get it into the glass slowly straighten it out then rock it around with almost no pressure- let the weight of the drill be most of the pressure. Keep the drill at full speed and you'll have no issues.
Dont use soapy water Find someone to do it for you. All you need is water
soap is a lube
he asked for tips and advice this is the diy section
he's asking how to do it not to find someone to do it
tons of videos on youtube
http://www.youtube.com/watch?v=87yJbAW32hQ