I think the guitar is tuned down a whole step (like a lot
of them), and the opening is based on the 

A6/9:  X04200 chord.

Instead of:
-------------------------------------------
-------------------------------------------
-------------------------------------------
---2-2-2-2---------------------------------
--------------------0-0-0-0-2-2-2-2--------
------------3-3-3-3------------------------

Tuned down one whole step.

It would be:  A6/9:  X04200

-------------------------------------------
-------------------------------------------
---2-2-2-2---------------------------------
---4-4-4-4--4-4-4-4-4-4-4-4-4-4-4-4--------
------------0-0-0-0-2-2-2-2-4-4-4-4--------
-------------------------------------------

The rest of the chords would just have to be knocked up
a step to compensate during the rest of the song (making
"C", "D", and "Am", "Bm" etc..., but I think this sounds
better.