Call JAL's toll-free number at 1 (800) 525-6453.
Or online. First you need to get the JAL PNR from AA for your itinerary. Then head over to
JAL's American Region website. Click on View My Reservations and enter these info: JAL PNR, Flight number, Date of boarding, Family Name, Given Name. Voila!
(I don't know if you need to be oneworld elite to be able to do the above.)