SAP HR - Mass uploading

Hi ,

I have one question about mass uploading employee data to SAP HR. There are a lot of discussions for the mass uploading in this forum. One of the solutions is about using BDC with the transaction code PA40. My question is how to create employee ID in the BDC. I only know Employee ID can only be created while you perform the PA40 action from the front-end manually. Thanks for the help.