Didn't he have savant syndrome - ie. his brain was wired differently than ours? I am not a neurologist, and I can't explain how his mind worked (I doubt if anyone can) - but I think that question 'how to gain mental abilities of Kim Peek' is similar to 'what can I do to get autism'. I know it sound harsh, I just want to say that you probably can't gain this kind of abilities from any amount of hard work.