Check the post from Sandra D. a month or so ago. http://www.mamasource.com/request/6140284202316201985
One of the moms (I think her name was Heather) gave a great idea. Instead of jumping away from the bite and allowing her to YANK away, hug her INTO your breast, covering her nose and mouth with your breast tissue until she opens her mouth to cry. Then relax your hug and CALMLY say something to the effect of "Oh, I'm so sorry. You were really hurting Mommy. Are you still thirsty?" Then offer her your breast again. If she bites again, I'd hug her into the breast a 2nd time and when she realeases, say "Oh, I guess you're all done." Then close up shop, so to say, for a few minutes. She SHOULD quickly learn that biting isn't fun for either of you.
I hope it helps, and congrats on your desire to keep nursing~ J.