If for some reason you can't print your BP in advance, find a gate that has a Lan flight departing and ask for help. (I don't think they have a dedicated service counter there). If you have any access to the AA lounge (OW status, flying LA in J), go in there for assistance. The airport is pathetic. If you don't have RCC access (or if it is closed) you may want to consider a day pass for the AA AC. It is nothing special at all, nor are there any showers, but the terminal is a dump.

(After posting, I see you are a 1K) - ok, the RCC has limited hours - go in there if open, and as a 1K, maybe a nice agent (they are usually quite nice in there) might be able to help you track someone down to check in for the LAN flight, and you'll have a place to camp out for awhile.