Stay on the east coast man. My dad lives in San Diego and I have friends in LA...every time I go see them there's a dentist office in every shopping mall, it's waaaayyyy too overserved. Unless you're getting an associateship and then buying the practice, I feel like opening up a practice in CA is suicide. Find a nice suburban place to practice in on the east cost, make tons of money and then you can fly to CA on the weekends : )
Oh, i guess to answer your question, it's very hard to take a license exam if it's not offered at your school. You have to arrange to get the chair time and tools AND get your patients that need the apropriate treatments. Also, CA's licensing exam is supposedly one of the hardest in the nation so you wouldnt want any adverse variables to screw you over. If you're 100% set on practicing in CA, you might really consider going to a CA state school (not that it's a big loss as they're all quite good).