Do you mean a bullnose corner like this one?:
I wouldn't recommend using PVC as I don't believe that the mud, tape, etc... would adhere very well and that the finished results would look, well, pretty crappy.
P.S. - There is a drywall section here, http://www.diychatroom.com/f101/

I wouldn't recommend using PVC as I don't believe that the mud, tape, etc... would adhere very well and that the finished results would look, well, pretty crappy.
P.S. - There is a drywall section here, http://www.diychatroom.com/f101/