Doctor Bob introduced chilli vodka to the TWJC convention & partygoers a few years ago. After Peewee's unfortunate episode in the renegade tent at BJC2002, chilli vodka reached legendary status.
Try & get the best quality chillis you can, about 100grams is enough for an average sized bottle. The quality of vodka is not that important. Fill the bottle up with your chillis, then leave it to stand for a week, most of the heat will be absorbed within an hour or so but the flavour takes a lot longer.