If you work for a USA 121 carrier you can jumpseat on most USA 121 carriers, some allow you to jumpseat int'l.
Forget about jumpseating on international [non USA Part-121] carriers, because it's unheard of; and even with occasional exceptions as mentioned, [IB-Iberia], it's completely unreliable.
You're best solution would be to have your carrier arrange an I.D. 90% ticket with a foreign carrier that has a reciprocating staff travel agreement.