Run the wires down to one of the rear lamp clusters, hide them behind trim if needed to look neater.
If its a normal bulb type brake light then it doesnt matter which way round the wores go.
If its an LED type brake light then you MUST connect the wires the correct way round else the light wont work.
Connect the - wire to the earth wire on the plug on the back of the lamp cluster or any other body earth thats nearby.
Connect the + wire to the wire that feeds the brake light bulb.
Either look in a Haynes manual at the wiring info or using a test meter / lamp find the wire that has 12 volts on it when the brake pedal is pressed.
Lee
June 2007