I'm trying to get this done myself. You have to go here:
http://oag.ca.gov/cures-pdmp
Click on PMDP registration on the right side of the page and then Pharmacist. You fill out the registration form, print it out and have it notarized. You will need a photocopy of a government issued ID, a copy of your pharmacist license and I think a copy of your store's DEA registration. You need an email address that is only accessible to you which you will need to verify within 72 hours.
I tried to register a couple months ago and abandoned the process before I sent in my forms. This was a big mistake because the site wouldn't let me try again and the help desk is very difficult to reach on the phone. I advise completing the process right away once you start it. I'm not sure how you access the database at work because I haven't got that far.