I wired my light to come on with the bright lights. If you do it that way you don't have to run wires inside the car. If you want them on a separate switch it's still not hard you just have to find a place to run the wires in to the passenger compartment. I believe out motoring sales brackets.
Is your mini a second Gen? If so take a look here. Out motoring has several lights to chose from and they have the brackets near the bottom of the page.
http://www.outmotoring.com/mini-cooper-accessories/1-lighting-tint-lens/
