Thumper used to do massive moults too.
I did as biscandmatt 1 very gently using the sides of my fingers so I didn't pull hard on fur that was still attached.
I also used just the end of a comb, the fine tines. I tried to mimic a bunny licking him, at the moult line, & got much more out than a brush. He tolerated it better than a brush too.