You first need to have contacts within the banks. These are high level people who have access to REOs or non-performing assets. These people get the info before they are given to asset managers who are either 3rd party vendors or internal to the bank.
Now once you got the contacts, you will need to have proof of funds and be able to buy bulk before they give you a list to look at. The minimum I've personally experienced is 250k/month and the assets are spread all over the states, not just in California. The California assets sell for 90% of BPO or appraisal.
Asset managers list to real estate agents in order to get the best possible price. They don't deal with the general public, at least based on my experience.
As a private individual, your best bet is to buy short sales. Then I would look into discount bids at Trustee sales where you have first hand knowledge of the properties.