The best I've got for you is I believe it's in Ab and the progression, of the song, is a descending progression.
So, it'd start (using the number system):
1-7/5, 6, 5, 1 (2,3 walk-up), 4 etc.
That's just going off the top of my head. I could be absolutely wrong, though.

Let me add that I think the progression is similar to Fred Hammond's, "No Weapon".