I found a review on this mouse
HERE which you might want to read. The reviewer actually states "it does begin to strain the wrist after using it for a while. This feature would be very useful in a presentation, but is certainly not for gaming."
It sounds like you have to press a button on the underside of the mouse (much like holding a phaser) in order to move the cursor with it. This would allow a rough sort of calibration, but some hacking would be necessary so that you would not have to hold the button continuously while playing.
The biggest problem is that with any type of gun (such as a lightgun) that you can hold freehanded (as opposed to a fixed positional gun) the natural tendency is to sight the gun as you would a real gun, rather than using the onscreen crosshairs. With positional guns, you tend to use the crosshairs like a laser-sight and just shoot from the hip.
Here's an example: Try playing T2 with a mouse. Move your targeting reticle to the center of screen. Now pick up your mouse and place it back down in the middle of your mouse pad. The mouse is now roughly calibrated, in that it will be in roughly the same position on the mouse pad as the reticle is on the screen--as long as you never let it touch the edge of screen, or let the mouse lift off the pad.
Now try aiming off screen, say, to the left. The reticle stops at the left edge of screen while the mouse continues to move left on the mouse pad. Now aim back toward the center of the screen. Most likely, the mouse will no longer be centered on the mouse pad. It must be calibrated again in order to be in correct alignment.
Now with the gyro mouse, you could basically do the same thing: stand in front of the screen, aim your gyro mouse at the crosshairs, then press the button that moves the cursor. Assuming you've properly set the sensitivity in Mame to the proper settings, you'll probably get a somewhat accurate aim between the mouse and the crosshair--until you let your aim get sloppy and the crosshair hits the edge of screen. Again, you have to continuously re-calibrate the gyro by releasing the button, aiming the mouse at the crosshair, then holding the button again. If you thought having to calibrate the Act Labs every time you start a new game, consider recalibrating every few minutes or seconds!

Lightguns exist for a reason. And considering you can get 2 of the Act-Labs guns for less than the cost of the gyro mouse ($79.95) why would you bother with a hack that has so many problems?