Hi Cameron,
I don't know of any utility in the WeBWorK distribution that does this. However, I have a couple of scripts that I use to do essentially what you describe that I'd be happy to share if you're interested. I'm sure that none of them will be what you really want, but they may provide a good place from which to start.
Gavin
WeBWorK Main Forum
Placement Exam
This forum has a limit to the number of forum postings you can make in a given time period - this is currently set at 10 posting(s) in 1 day