Set it up with the AA RTW desk and tell them it is to be issued in HKG and paid in HKD. The only problem is that the AA HKG office will not accept faxed or emailed cc information. Still, it makes for a nice long weekend to do a HKG run to get the ticket (just make sure you know the hours that the office is open and that you don't target a public holiday).
From a curiosity standpoint I would like to know if this works. Just last fall I had to go to YYZ to reticket my not yet started CirPac as the AA RTW desk said CX requires tickets to be purchased 7 days out.
You may want to double check with them so you don't encounter any unwanted surprises.