As far as I understand it, yes. It would not only left click but hit what ever button you had programmed such as "1" for P1 start.
Sorry, had a brain fart. In Mame, you can assign mouse buttons as keys, so in effect you would not wire your mouse buttons to the keywiz. Sorry about that, it's been a long time. I had two buttons on the side of my first cp. One was a mouse button, the other was a button for vpinball. That's why I was a little lost there.