Originally Posted by elitelite

Hijacking my own thread to share the approach I took for a JAL flight booked through my account in a different loyalty program (Alaska Atmos Rewards) where I still wanted to use the oneworld Emerald benefits from my AA EXP status. What I did was book for a separate traveler from the account holder (me), but with my exact name and personal information, except I listed my AAdvantage status in the reservation instead of my Alaska status. The Alaska reservation reflects oneworld Emerald, and I'm fairly confident that will show up on my JAL boarding pass as well.

At any rate, that's the approach I recommend taking if doing the same thing with JAL Mileage Bank. If JMB doesn't have a field for loyalty program in the booking or reservation management flow, then I'd just give them a call to add it or do the same at the airport.