Could use some help with mounting my gauge.

I just took out my ash tray which was a pain in the butt. The two screws underneath...wow they were tough to get at.

Anyways, I have a 99 Grand Prix GTP. I want to mount my gauge there but have no idea how to. Has anyone done it? Do I need to make my own bracket? If so, what can I attack it to?

Also, I need a power supply to run the gauge off of. There are three wires that powered the lighter and the light that were in the ash tray. I unplugged those. Can I splice my three wires for the Aeroforce Gauge onto those three wires? Will it be too much or not enough power?

Thanks