I seem to recall seeing that gun brought up on the forums before (can't find it though), but as I recall the answer was No it won't work with MAME. Also that fact that it says it works with House of the Dead and Virtua Squad 2, makes me think it's not compatable as well, as both of these are games handle the mouse in a special (non-standard) way. The act-labs guns didn't work with these two games, until they released a special fix (see
here).
I also noticed that act-labs is now advertising the fact that you can get two PC USB guns working in Analog+ MAME. (Way to go Urebelscum & JerryJanis!
)
I just purchased two act-labs guns myself, and hope to get them working soon. I was wanting the PC virtual guns, as they look better, but my wife convinced me to get the "ray guns" as the kids will be playing with them on our arcade as well. At least she didn't say no to them altogether. On the bright side the act-lab guns are supposed to be more accurate, and they seem to have more user support behind them.