[IluvLucy]

I went thru this when Lucy was little. What finally worked for me was to gently hold her nose and mouth in one hand and say NO firmly. I did it every time she tried to bite (she was always playing when she did it). It didn't take long and now, even now when we're playing if she starts gnawing on my hand I can just say no and she immediately stops.

I think the key is to stop it early.