I just did the jumpseat deviating from deadhead ATL-SVO. It was a greenslip, so I had to go. You need to book it and be at the gate 75 minutes prior to departure so you can be on the Gen Dec. In my case the agent said to just write my name in which won"t work with the strict Russkies. So I called the chief pilot and he made sure the station manager was aware, and she met me on arrival in Moscow.