Timely post; I have a similar situation in early March and was wondering about access.

Arriving into LAX early morning on CX J. Was going to spend a few days in Los Angeles with friends before flying home to SFO. But now need to be in SF that night. So I'm planning on sticking around LAX with a noon-ish AA flight to SFO.

Separate PNR's, but arriving on international long haul J, with an AA flight that same day, I should have access to the oneworld business lounge at LAX... right?