to do that you need to drill in the glass, a regular drill bit will work, but it is recommended you use a glass drill bit... either way, you need to wrap a few layers of either duct tape or masking tape (for some reason the clear plastic tape doesn't work) around the spot to be drilled, keep a steady drip (not pour) of water on the exact spot being drilled and go slow.. after awhile you'll have your holes, just make sure you drill at the correct angle (w/e angle the bowl/stem is going to go in, is the angle you need to drill with, also make sure you're drilling atleast the size of the stem or if you plan to go professional and use a grommet ((rubber peice around 'inside the hole' that the stem goes through)) make sure you alot 1/8 inch for it to fit in as well....)