Jkeys, I tried to figure the chords out on that "O, O, o, o" part. I think it goes like this:
Key-Ab minor
LH/RH
E/EbAbB- O
Eb/DbGbBb- O
D/DbGbBb- O
Db/BEAb- O
(Repeat)
The part the sopranos were singing was:
Eb- O
Db- O
Db- O
B- O
I hope this helps. Somebody please correct me if I'm wrong.
God Bless