Wiring connections for boost gauge.

I'm after some advice for wiring in my boost gauge.

I'm after fitting the gauge itself onto the A pillar, I gather I can run the wires to the light switch for both the ignition live and also the power for the lights.

However, would I be able to wire the gauge into the standard dimmer switch so that it can be dimmed along with the dash lights? If so does anybody know which wire I will have to splice into for the dimming feature?