Nothing you have to do. Once you are a pilot for XJ (Mesabahhhhhh). You will be in the CASS system. When you go to "jumpseat", you will show your ID, they look in the computer, a voila!!! If the Captain agrees, your in!!!
Nothing to do on you side to "get in" the system. But you have to be "employed". I don't know if that is before, or after your checkride, or what.