This is not a big deal. On line, meaning main line or group, if you, in you fist, have the paper work filled out, the C/O says ok, you have a ride. If there is a seat in back, you are welcome to it. Now if my wife is trying to nonrev on the same flight, she gets the seat first, because you have listed for the jump seat, not a seat in back. So eveybody gets to go. If you are an off line pilot, there must be an empty seat in in the back for you. And you go behind all norevs, and all off line employes on a ticket. If you are part of group, and can get to the cockpit before the jet way is pulled, the C/O can put you on the jumpseat without the agent's ok.
Again, only group pilots are allowed on the flight deck jumpseat.