I think what the OP means, that if a player does a backpass to him, can he do a keepy uppy, knee it and then catch it himself, as the ball is coming off the keepers own knee, rather than foot.
Pretty good question to be honest, I doubt it's allowed though - pretty sure there is a rule indicating that the keeper cannot pass to himself or something along those lines.
(I may have completely misunderstood the posts though, that happens a lot)!
Although I could try it on Sunday (hants cup semi final match) and see if I get away with it ;-)