For the most part banks and asset management companies are hiring the trash out companies and other vendors directly. The Agents are now only responsible for the re key of the home. Your best bet would be to sign up directly with the bank/asset companies to become a vendor. You can google the different asset companies or you can purchase the list of companies from bestreolist.com or other similar companies that sell these lists.
Your best bet is to advertise and talk to the listing agents that have your local foreclosure listings. Ofteen times they are responsible for hiring someone and getting quotes. Some of the larger REO's will hire thier own but mostly it is done by the agent who is going to get the listing.