After you post a program you can rename the text file to a .cam or any other extension your machine requires--this is standard windows stuff.
When you post in EZ-CAM you can change the directory where EZ-CAM posts the G-Code File. When you change the directory you can select "post processed programs" in the drop down menu for save as type. Name your file and place a .cam extension (or again any extension a machine may require). When you are done click the "Save Options" button. Now every time you post the extension it is saved to the last one you used.