Key: G
Tuning: EBEEAE - G goes down, D goes up (VERY SLOWLY!)
Capo 3
Timing: 3/4

E----------------------------------|
B-5--5-7-(b9)-7-(b9)10--10-(b9)7--(b9)7-5--|
E----------------------------------|
E----------------------------------|
A----------------------------------|
E----------------------------------|

x3

THEN

E-------------------------------------|
B-5--5-7-(b9)-7-(b9)-10--10-(b9)-7--(b9)-7-5--|
E-------------------------------------|
E-------------------------------------|
A-7--7-(b9)11-(b9)11-12--12-11-(b9)-11-(b9)7--|
E-------------------------------------|

x3

For those who are interested, the second bit is an octave up,
and the entire song is based in the key of G major.
David uses the tuning to simulate the celtic feel.
If you don't fancy tuning your guitar like that,
play the riffs as quite literally just the notes indicated
- you don't need to use a capo if you transpose it up 3 semitones
(5=8, 7=10, etc etc).