B6 does take jumpseaters in the back, as many open seats as there are. Oversale situation: you are out of luck. Good luck trying to find someone who knows about jumpseating int'l when you're actually outside the US. Best bet is buy an ID90/ZED. That's just personal experience though. "talk to the captain" won't work in many of these places because the gate agent isn't going to give you anything to let you go through security. The jetBlue number to list for a jumpseat is a good place to start for airport specific procedures. Dont' have it off the top of my head, but airlinepilotcentral.com is a good place to look.