If the IT department is worried about server load, perhaps you could arrange to get a data feed once or twice per day (overnight would probably be best).
Tried that. All they would have to do is put all the data on one page instead of me having to make 130 requests(one for each department). They refused saying they don't have resources. I've tried to be as nice as I possibly can be and they've been as dick-like as they can be.
My last resort would be to ask our user-base to call the IT office and voice their support.
Why isn't that your first resort?
Writing in that line or two of code would also take care of the school's strange DoS concerns.
Of course, if profit is the goal, this isn't an option (though it doesn't look like you're trying to monetize this... kudos for that).
Also, this removes the exclusivity from classhunt (as any student would see this while browsing the schedule online). I'm sure you can make more inferences about this option. (Less social capital in the business world as you have nothing to point at and say "I did that," etc.)
If you don't have to worry about getting thrown in jail, I wonder why more people aren't doing it? ;)
Anyway, to answer the OP's question...is there some combination of POST options that loads the entire class schedule at once? I know my school's (U of Alabama) system had a form where you could select all of the course departments and load the entire schedule on one page.
Also, do you really need to reload the data so often? If the IT department is worried about server load, perhaps you could arrange to get a data feed once or twice per day (overnight would probably be best).