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----------------


If you have heard this song you know how slow and tripped out sounding this riff is. And the spacing for the notes isn't right, I did it like that to fit it on one line. Listen to the song for actual timing. Later, I'll do some of the longer, more elaborate stuff by Down. I hope this'll do for now. Later.