It isnt hard, just do it like you would on a domestic flight. You might have to go to ticket counter to pay departure taxes though. As far a jumpseat go...
747 - 2
767 1 or 2 depending on the model 400's have 2 I believe
777 - 2
realize however that on international flight those jumpseats make be occupied by additional crewmembers thus necessitating a seat in the back. For my money the 777 is the way to go if you have to ride in the back....very comfortable, especially in business class...
One thing to be careful with jumping international is who you go with. For example: Continental has a policy now that only allows their employees (or COEX) to jump international. American also only allows certain carriers to jump intl. Kind of a pain and no one understands it, what the hell is the difference in domestic and intl. anyway when it comes to jumping???
I've bitched to the jumpseat commitee several times on this issue because I go visit family overseas alot and get stuck with these problems. So far no one has any viable explanation for it.
Good luck and if you have any info on getting on or reasons for not getting on let us know.
Unless your ID can be verified electronically, there has to be a seat in the main cabin for any jumpseater. 767s have 2 jumpseats. Jumpseating internationally is tough. With the current severely cheap airfares, almost all the flights I've been on have been packed and we've turned jumpseaters away.