Riff A (this is the same for both bass and guitar)
E|-------------------------------|
B|-------------------------------|
G|-------------------------------|
D|-----3~------3~------2~-----2~-|
A|-------------------------------|
E|-1~------1~------0~-----0~-----|

Riff B (slight variation on Riff A)
E|-------------------------------|
B|-------------------------------|
G|-------------------------------|
D|----3~----3^----2~----2~-------|
A|-------------------------------|
E|-1~----1~----0~----0~----------|

Riff A x2
Riff B x2
Riff A x2
Riff B x2
Riff A is played for the rest of the song until 
all the feedback and vocals come in at the end