Changing Work (Z) Visa to Student (X1) while in Beijing. Possible?

Hi I'm an American on a Work type (Z) in Beijing right now. I will be going to grad school here Beijing and need a student (X1) type. I have all the paperwork from my school. Is it possible to change it without having to leave China? Such as doing it at the PSB here in Beijing? They weren't allowed to answer this question over the phone. Thank you!