Okay, I've been able to solve the scheduling problem another way. Since each seminar on a particular topic is offered for a consistent number of days, (i.e. underwater basket weaving is always five days long whereas left-handed smoke-bending is always offered for three days) I set up an initial occurrence and set it to recur every day for five days. I then shift-clicked all five occurrence and copied them. I then went to the first day each seminar was offered and hit paste. Clean up of the seminars I don't take is going to be a bother, but I think this will work.
Still, if there were a way to import a semicolon delimited text file into iCal, I think it would make some things a bit easier.