Just show up at the gate -- I recommend 45-60 minutes prior. Depending on the station, the agents will likely be the same ones at the ticket counter that are at the gate. If its one of these stations, you should be able to "list" and/or get the forms at the ticket counter. This would be recommended because nobody will be at the gate until boarding begins. Make sure you hang out so that the crew sees you on the turn if you have ANY issues with the gate agents. We have some agents that don't understand how to do jumpseat listings, etc. All you need is the "jumpseat form" and they are supposed to do the CASS checks. If there are CASS issues you still can take a seat in the back with CA approval. PM if you want station specifics and loads.