If one is a Plat or ExecPlat [i.e. oneworld Sapphire] flying with an AA international ticket even in coach, you can enter the ACs if not a member on both the originating US/Canada/Mexico flight as well as at the international gateway. You will be given two drink coupons at each AC. However, if AA uses a non-oneworld partner airline's lounge at the international boarding point, then you cannot access the lounge based on your international tickets unless it is F or J [or upgraded variants of those classes].

By the way, what does AA consider TransCon? NYC-SFO/SEA/SJC/LAX? ORD-SFO/SJC/LAX/SEA? MIA/LAX/SFO? DAL/LAX/SFO/SJC/SEA? YYZ-LAX?