Show up early at the gate for united, there's no way to list. The gate agent should be able to handle it. For Air Canada, you have to call the employee travel center 800-413-1113, and make a reciprocal jump seat reservation, costs around 50 bucks I think. Then check in at departures to get your boarding pass to go through security. You can't use the kiosks as your reservation gets processed adding FD(for flight deck) to your name. (Smith=FDSmith) That's about it. Gate agent might ask to see your ID and confirm with the crew that you're good to go, don't forget to say please and thank you, mind your P's and Q's and you might get yourself a seat in first.