You can install in cloth or leather seats.
This is the kit I installed:
http://www.sportsimportsltd.com/heatelcarsea.html
Yes, you can find kits much cheaper but this one is electronically controlled with a shutoff timer, is MOPAR licensed, and unlike cheaper kits this one has 3, not 2, temperature settings.
I put the switch on the removable panel on the dash that is convenient (close) to the fuse box. The switch looks like it belongs there, it is perfect and looks OEM.
The link I posted has a video which I watched before I made my purchase. The video convinced me how easy it was to install the heater.
I'll take some pics of the switch location and post here sometime after Christmas.