Ah yes...that makes total sense.
Well....you could try doing what you suggested....but I think you may end up with errors because when you are installing the driver for the 7950 it won't be in the machine....or even if it was, you would have two cards in there....and that may cause problems with the driver install.
Obviously the best way is to hook it to a monitor with the 7950 installed....let the Windows drivers do what they do and then install the 7950 driver.