[Raymond]

Originally Posted by DonInKansas

Not really that hard; just pick up the phone and start calling ADs at local schools. They will put you in contact with whoever you need to speak to if it's not them that does the assigning. I've never had an AD tell me they've got too many officials.

Originally Posted by Snaqwells

I would talk to the people who assign the games you've worked. They'll not only know which officials are qualified to help you, but also which ones would be willing to do so.

I would try Google and the IAABO directory.