I applied in-person. The process took 2 weeks. I interviewed at North Orange County Referee Association (Anaheim Hills, CA) in Aug 2012
Interview
All you have to do is pass a 2 day, in class and in field, 4 hour class. For a total of 8 hours total. You also must pass the written multiple choice exam at the end of the class, and then go through with a total of 2 or more mentoring sessions. That is about it, it is a pretty simple process.