Depends upon the lounge, and the agent. At the CX lounges I've used, for example, a BP would suffice. I've also used just a BP at BA lounges in various places at times. Other times a card was required. It's certainly worth trying, and pleading your case since you are legit. But be prepared for "no."
Cheers.
that almost sounded like...... well.... like when my new girlfriend said
"not tonight sweetie, access not granted, I have a headache" 
(but she obviously wouldn't tell me go seek access elsewhere....
)
oh well... I'll just stick to AA's own AC, which are quite nice in some of the foreign airports I'm visiting next week.