I had the same issue, and here is the quick PS3 controller fix:
Download the motionjoy drivers and the program (at work now so can't remember offhand what the name is). Connect the controller and load the drivers as per their instructions. Set the controller type to Xbox and click enable. The buttons all map correctly to the defaults.
Hopefully that works for you. I set up the PS3 controller in about 5 minutes doing it this way this morning. Mostly just wanting to try out the interface.
Just as an update, there are very few working controllers at this point, really hoping they make this a little more robust in phase 4... After playing a fair bit of the Alpha, I got fairly used to using the keyboard/mouse though
Edited, Jun 15th 2013 10:50am by Grandlethal
95THF, 95DRG, 90BRD, 94BLM, 95BLU, 90COR - Retired: Nov 2011
Someday soon my friends, this ride will come to and end, and we can't just get in line again.