I got Mouse at 3 months. She was a totally wild kitten. I put her in my "kitten room" where there is no place I can't get to her. I would pick her up with gloves on, then hold her close to me so she could hear my heart. Then I'd start petting her. After 2 days she would let me hold her and didn't scratch. I think I was successful since she was very young. Anyway, with kittens it may be useful to "force" the issue a little bit.
After a month Mouse got a new home and was a totally mellow purring mush.
Good luck!:)