I figured this out in a few minutes, so it's not perfect yet. But it's a good start...
He's got the whole guitar dropped half a step (so Db, not D like a lotta Keller tunes).
Then the chords are as follows... Keep in mind they're all relative to standard tuning,
while the first chord is played as an F#, it's actually a G... cool? Watch the video
he voices a lot of the chords in First position bar for his hammer on stuff
F# - A - B - Esus2
F# - A - B (crazy trill hammer on thing)
Pre Chorus is something like
C#m7 - B - A - B
F# - A - E
F# - A - B
C#m - A - B
or something like that. Sorry this was semi rushed. As I work it out more I'll post.