This song has really catchy guitar: http://www.youtube.com/watch?v=fAM8iFMWWmw

I've been trying to play this song, and I have intermediary guitar skills (~master of puppets), but I can't figure out the quick parts in it, or the quick riff changes!
There is a cover of it too: http://www.youtube.com/watch?v=4XT8N_Zawh4 and the guy said he used a songbook, but I can't find the songbook either. I understand that just asking for someone to do it is not realistic, so I'm willing to try further myself, but I was looking for pointers on how to approach quick distorted sounds. The thing is, I always play by ear, and I can approach the sound, but I can tell it's not right. I would like to get it right.