A dorm student doesn't have to put up a mezuzah. mezuzot are the obligation of someone who lives in a place as if he owns it. That is why tenants need to put mezuzot because they are temporarily the owners of the place. Dormers, on the other hand, have use of their rooms much like they have use of the university library, or classrooms – it's part of the package the university offers. This means that someone dorming is not considered to be like a tenant and is exempt from putting up a mezuzah.
If a dormer wants to put a Mezuzah on his door and the university gives permission then there is no reason not to. However, because there is no obligation to do so the and the mezuzah should be put up without a Bracha.
