I had a declawed foster named Spliffy who was a very bad biter at first. I worked with her for six months. I would pet her, and watch her body language very closely. When she had enough she'd "box" you with her paw. I would walk away and try for another petting session later. Gradually she bit less and less. Not only was she declawed; she had had virtually no social life for her first 7 years and basically had to be resocialized.

BTW, Spliffy was successfully adopted in January, so there is hope.