Standard tuning
This is the main part of the riff (as far as i can tell). It's my first tab and I'll correct it as nesessary.
Any comments welcome :)

G|---------------------------------|
D|-----------------3-3-3-3---------|
A|-5-5-5-5-3-3-3-3---------3-3-3-3-|
E|---------------------------------|

I think that this is played 16 times before the riff changes.
I don't yet know what it changes too, but i'm working on it.