So to keep it simple, the whole song is based upon this little riff, you can play it in 
but it also works perfect in E-tuning

/ = Sliding to the note from a lower fret
For standard tuning in E          For tuning in C (no dropped tuning)
G|------------------------|    Eb|------------------------|
D|------------------------|    Bb|---/6-------------------|
A|---/7------1---0--0-0---|     F|-----------5---4--4-4---|
E|-0----0-0----1--------1-|     C|-4----4-4----5--------5-|

This is the riff played trough the whole song, sometimes the octave isn't played (most 
the time when there is any chant going).

There might be a little bass solo-part in the background, but I don't remember exactly

This might be enough to play the whole song
Listen to the song for the rhythm, but this should be quiet obvious

This can be used as a guitar tab aswell, if you do a harmonic on the upper E and a 
bending and use some power chords for the other notes