I'm not sure I understand the question here, I assume it isn't asking the DOS commands to copy source files.
You can move/copy source from one project to another using a batch script called ApplyPCF.bj (see Batch Refresh.pdf). This is about reorganising the complete Workspace project setup. It requires as input a PCF that you edit to define your project contents. You can get a base PCF by running the Batch Refresh Process (even if you don't add any source) and a BEGIN.pcf and an END.pcf file is created in the BRP\Reports folder.
Edit one of these to have the required structure and save it as MY.pcf. This, then, can be the input file for your ApplyPCF script.