Reread Rogers earlier advice. Time and LOTS of patience.
Hold him 3-4x day for 20-30 min.
How hard is he biting. Is he strong enough to draw blood? Or does it just hurt?
You're going to get hurt owning an iguana. I've had 2 adult rescues, and for iguanas they both were pretty laid back, but my arms have little scars across them just from them climbing and holding on. :(