Well I'm coming from the other POV with this one. My DS is continually bitten at daycare. He is a very laid back kid and doesn't make a fuss when the other kids (one in particular) bites him. The CCC have flash cards with DON'T BITE written on them and when the kids take a chomp they say it out loud and hold the card up to them. That child is then placed in time out (usually only for a matter of moments) and the bitten child is cuddled and everyone pays attention to them.

Perhaps something visual like a flash card might get his attention quickly and hopefully he will start to make the connection between the act of biting and the fact he is hurting you.

It isn't nice for either the parent's of the bitten child or the biter. I've been in tears many times of the bites and bruises DS has but I know that the mother of the kid who bites is trying her hardest to stop it happening so it makes a huge difference to me to know that they take it seriously.

Sounds like you are doing a great job and I'm sure it will register with him soon.

HTH
Spring.