I did but does it fit a reg rivet gun?

Most likely not. You'll have to be creative with a set of vice grips, and pliers or a tool of some sort to hold the rivet while you manually set them.

SlickGT1 (Denis) did a great explanation when he installed his running boards, refer to this thread for the same procedure when installing the new flared arch.

http://www.xoutpost.com/bmw-sav-foru...etter-diy.html