I honestly forgot how I did it, but I'm pretty sure it involved lots of calling to someone at the aviation department. In fact, I don't know if she's still in charge of the summer students, but when I first began, Amy Sand handled all of my troubles/questions when registering. Talk to someone at student services.
I took 102 in the summer of '04. I hadn't graduated high school yet, so I just missed graduation. In NYC, we graduate at the end of June, like on the 26th or somewhere around that time. The 102 session began at the beginning of June, so I just decided to come here instead. UND let me register and everything, despite not having graduated. I just explained my situation to someone at Student Services, and they were very helpful.
I'm really glad I did so because it's pretty hard trying to get into 102 in the fall semester. I shouldn't say it's hard, but it ends up being like half and half. I highly recommend you do it over the summer. It's a good time to start flying, not too many distractions (I mean it, because summer here is extremely boring).