Well I did it with method 3 because it's the one listed in the achievements guide. At first i thought it was really difficult and couldn't get past 10 chomps. After some practice i noticed a few things:
1) Your position matters... try to be just where the author of the video is standing. The tower needs to be visible so that you have some space to move around.
2) You don't need to scare the bad guys... you just need to make sure you can be over their head after you head chomp the one you're riding.
3) Enemies move at 3 different speeds... so before attempting to head chomp, make sure you calculate exactly how much time you need and where the enemy will stop.
After i noticed  it was a piece of cake.
Last edited by Mastermnd; 03-31-2009 at 10:43 PM.