I just booked an award flight on Cathay Pacific using AA miles. I had to call CP to get their five-letter locator code (a different one than the AA six-letter locator, for the same reservation) to view the reservation on-line on CP's web site. Also, my return flight is on a paid ticket with one segment on CP and one on AA; when I tried to get a seat assignment the first time they said they don't do economy seat selection in advance, but then it worked when I called back and asked "do you allow advance seat selection for OneWorld Emeralds?"