I want to apply for a working Z visa from Korea. U.S. citizen

I have been teaching in korea since Nov.2011, English academies. Can I apply for a working Z from your consulate? I am in the process of being hired by a English institute franchise in Shanghai. I want to avoid returning to the U.S. to get a Z is possible. I understand it can be done through a currier service and travel agent. Gratefully yours, Oren Romo 010-5559-5301