I think we ought to get the terminology correct, here, as we run the risk of confusing some Ppruners, especially Americans.
To most professional aircrew, the term 'Jumpseat' refers to the industry practice of offering one of the observer's seats in the flight deck to staff (either your or another airline) for the duration of the trip. In America, particularly, this privilege is available on production of a current ID from a participating airline. It is less common in Europe. Strictly speaking, what you are looking for is a flight deck visit, albeit an extended one.