I read this post from HippieLawChick on another thread and thought it might help you,
"I did this with the school I now attend. I applied late and was put on "hold" (like a priority waitlist they said) I sent an email to the Dean of Admissions essentially saying, "I haven't heard from you yet regarding my admission, but I wanted to clarify that for X, Y and Z reasons, __________ is my first choice for law school. I will withdraw all other applications immediately if admitted." I ended up getting in."
I think visiting in person could help too (even if you have already been there). Also, is there any way to find out where you stand on the waitlist, how many students usually get in off the waitlist, and when you can expect to hear? Asking these questions in person might allow you to gauge the answers a little better (it is hard to pick up underlying meaning from email).
Don't know if this helps, but good luck with everything.