Try something like these, http://amzn.to/1JURIfZ
Start with an 1/8″ 2 flute bit made for wood. when you have a few cuts under your belt you could probably move up to a 1/4″ and work faster. like this http://amzn.to/1LjTpZP, on a 1/4″ you might be able to get away with 4 flutes.
Drillman 1 on ebay has an amazing selection with prices to match, good guy. My advice is stick with 18″ at first, only move to 1/4″ when things are running smoothly.