The whole song works around this chord progression:

  Dmin7  C#min7  Cmin7  A#7   A7
E|-x-------x------x------6----5-|
B|-10------9------8------6----5-|
G|-10------9------8------7----6-|
D|-10h12---9h11---8h10---6----5-|
A|-x-------x------x------8----7-|
D|-10------9------8------6----5-|

The hammer-on for the first three notes essentially removes the 7th from the chord. If 
want you can add a bit of percussion in between the first three notes to pad it out a 
and that's pretty much it!