The mic input is an 1/8" jack on the back of the sled, attached to about 8" of cable. You may or may not be able to "Easily" hook/un-hook the mic-rig, depending on the design of your car.

I would recommend simply getting two mic kits, one per vehicle. I'm lazy enough that hooking up my earphone/mic doesn't get done, let alone having to rig up a hands-free mic every time I changed cars.

D