They would go through the same security as a passenger does on the way to the gate. They probably wouldn't get as much attention as a regular passenger, particularly if they were in uniform. Still, if they had something that was prohibited, they'd still be stopped, even before Sept. 11.
As far as the protocol of getting on a jumpseat, the industry isn't standardized but it's all pretty similar.
If your airline has a reciprocal jump seat agreement with another airline (and almost all majors are reciprocal with one another; little known fact: most airlines average 30- 40% of their pilots commuting by air to work) then you show up, identify yourself, fill out a short form, get introduced to the Captain and away you go.
This is no longer the case, however. Sept 11 changed that.
We as an industry were complacent about the jumpseat, no question. In hindsight, we all look pretty stupid, particularly since we had all heard reports of uniforms and id's being stolen in Rome not too long ago.
It was a "professional courtesy" and there was no "stump the dummy" quiz to determine legitimacy as pilots. It was sort of accepted if you got that far, you had to be bonafide. A cursory check of a few licenses/documents with the Captain and you were accepted.
Obviously, a big mistake.
