http://www.waytoomany.com/vids/weed/corazon_bong.php

Here is a kick ass video of a dude making a sweet piece out of a Corazon Tequila bottle. You can buy a glass drill bit at Home depot for about $12. I went to the head shop and bought a stem first to make sure I bought the proper size bit.

Make sure when drilling you keep the bottle still and use thick towels to reduce vibration. Also practice first on crap bottle with thick glass b4 you try to use a prime bottle.

Good Luck