Although I don't have any biters right now, I have in the past. I was never able to stop them, just make the event a bit less painful for me. I would yell ouch in a very high pitched voice, something like a kitten does when it is in trouble. It seemed to make my cats let go. I am not sure WHY they did it, but they did. One would actually hop on the back of the toilet (ahemmmm) and bite my head/hair while I was a captive audience.

"No bites" is what I say to Miley when she gives it to me, usually during play. I also put my entire hand over her head and hold her still for a few seconds to get control over her. She really isn't bad with it.

Juni is biting now but just in play and not hard at all. She likes toes and fingers. Right now I look like I tame lions for a living! Scratches everywhere on my legs. I do love that Juni girl though, so I am hoping when she grows up she will get over the kitten thing....

My advice, start reacting to the biting - and discouraging it with whatever method you feel comfortable with....

Wearing hockey equipment would be an alternative.