Ok, this is on an acoustic and I play it in Drop D(not sure if that's how they do it but it sounds fine either way.

Main riff

E|------------------------------------------------------------------------
B|------------------------------------------------------------------------
G|------------------------------------------------------------------------
D|-------2-------------2------4--------0-------------0-----2--------------
A|---2-----2---2---2-----2---------0-----0---0---0-----0------------------
D|-2---2-----2---2---2-----2-----0---0-----0---0---0-----0----------------