You must be prepared to show your boarding pass and frequent flyer membership card, with oneworld Emerald or Sapphire tier status, to access a lounge. Access is available on the day of travel (or before 06:00am the following day), at the airport from which the oneworld flight on which the eligible customer is travelling departs.
https://www.oneworld.com/airport-lou...-access-policy
BA at their many outstations, AA Flagship, CX at SFO, JL HNL, QF LAX have all accepted a boarding pass with AS number attached and separately a foreign OW status card for entry. AS is the outlier here