I'm pretty sure you file down the little bar that resets the slide every time.
You'll have to look into it further as I'm not positive. Google will bring up results if you search.
I wouldn't recommend doing that though because a pistol is used as a sidearm and having it full auto will put quite a bit of stress on the gun's internals.
It was designed to be semi so if you mod don't expect it to last long.
Word on the street is anyways.
-Brian