Hey, so this is just a note about what the three wheel drive is supposed to be. Most of the code, at the moment, is derived from Patrick's 4 wheel stuff. There are a few links below that I found interesting and helpful(there's at least one additional one in the drive), please take a look at those.
Note that the best links are http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.99.1083&rep=rep1&type=pdf and https://robotics.stackexchange.com/questions/7829/how-to-program-three-wheel-omni