An illegal commute would be, for example, only giving yourself one leg to get to work that is scheduled to arrive only 20 minutes before your show time...not that I ever did that or anything...

You don't schedule jumpseats in advance; you show up and hope that there are open seats in back, you're the only one requesting the cockpit JS or have priority over other interested people. Priority depends on what company you work for, what airline you are trying to jumpseat on, and your DOH.