Cool song.  This is how I play it.  Riff 1 varies a few times.
USE A PICK!  On Riff 3, the two mutes (XX) are basically pick clicks.  It's
fast, so watch out.

   Riff 1.
G:---------------------7--|
D:---------------------6--|
A:--7---7--r--7-7-7-------|
E:------------------0-----|

   Riff 1 (variation)
G:-------------------------7h9--|
D:---------------------7h9------|
A:--7---7--r--7-7-7-------------|
E:------------------------------|

   Riff 1 (variation)
G:---------------------7/8-|
D:---------------------6/7-|
A:--7---7--r--7-7-7--------|
E:------------------0------|

   Riff 2.
G:------------------------------------|
D:------------------------------------|
A:------------0---------2-----0-------|
E:--0----3-----------------3-----0----|

   Riff 3.
G:--------------------------------------|
D:------------0--------------------------|
A:--7-7-7-7-7---------------------------|
E:--------------5-7-5-XX-3-5-3-0-0-0----|

The order of riffs:

Riff 1 x20  (This riff is played a little different from time to time)
Riff 2 x2
Riff 1 x8
Riff 2 x2
Riff 1 x12
Riff 2 x2
*Guitar enters playing "riff 3" 4 times, then bass enters:
Riff 3 x?  (A lot of times.  Some of it is just bass and drums together.

ending piece:
                   x8  / / / /
G:-------------------|-/-/-/-/----------|
D:*-----------------*|-/-/-/-/----------|
A:*-7--7\-----------*|-7-7-7-7--7\------|
E:---------0-0-0-0---|------------------|