On my recent KLM trip KUL-CGK-KUL on the KLM 77W we had the same crew on the outbound and inbound journey.

When I told them that the only reason to take the flight was to try the new WBC product on the 77W they started laughing, and soon after the FA went to ask the pilot if I could have an mid-flight cockpit visit

That said, I have also sat in the jump-seat from LHR-AMS. That one was a bit lucky as I knew the captain. He did however do the required paper work so I believe there are certain guidelines to be followed.

Gajan