I have no idea what tuning Mark really uses on this
song. It's in Bb major, but it's really hard to play
with open tuning. I suggest drop-D tuning with a capo
on the 3rd fret. I'll tab this out that way (with the
3rd fret corresponding to the open 0's)

(Drop-D, capo 3rd fret)

Intro and Interlude:
all variations of this
Bb              Eb (strum the chord
                    occasionally)
---------------|-------------|
---------------|-------------|
---4^-----4^-4-|-5-----------|
---------------|(5)----------|
---------------|(3)----------|
5-----5-5------|-------------|

Verse:

Gm          F                Bb
----------------------------|------------------|
--------------------3-------|8---8--8---8-8----|
----------------------4-----|7---7--7---7-7----|
----4-5---4-----4-------5---|5---5--5---5-5----|
--2-----------0-------------|5---5--5---5-5----|
2-----------0-------------0-|5---5--5---5-5----|

Chorus:

(play CD for rythm)
Bb       Bbmaj7   Gm  F    Bb
--------|--------|--------|--------|
8-8-8-8-|8-8-8-8-|--------|8-8-8-8-|
7-7-7-7-|7-7-7-7-|--------|7-7-7-7-|
5-5-5-5-|4-4-4-4-|5-5-4-4-|5-5-5-5-|
5-5-5-5-|4-4-4-4-|2-2-0-0-|5-5-5-5-|
5-5-5-5-|4-4-4-4-|2-2-0-0-|5-5-5-5-|