I have installed several heaters in factory seats and they are pretty easy. Buy the heaters (I have gotten several sets off Ebay for $150.00), they are simple little heating elements made into a pad.
Unbolt the front seats and take them out of the truck, I usually take them into my living room and work on my carpet. Unbolt back of seat from bottom if you are able to. Remove the "hog rings" (metal clips holding leather or cloth to frame) and pull the covers up,
be carefull they are tight. You only need to pull the cover up enough to get the heater element in the middle of the seat (back or seat), sometimes just taking a few hog rings out I can put my arm under the cover to position it and notch the foam out. Notch the foam out for the heaters (if needed depending on heater height) and run the electric cord to the bottom of the seat (if heater is low profile and you dont see it under cover just take knife and cut a slit to run the wire in). Run 12V from battery to a place where you can mount a switch (last truck I used the upfitter switches saves alot of time and looks factory) and run the heater wire to the switch or switches if you do both front seats. Put seat covers back on (Leather will need to be at least 70 degrees or more to stretch back over foam and frame) using new Hog rings (will need to buy Hog ring pliers about $10.00-$20.00) and bolt seats back in.
It takes you about 6-8 hours depending on how fast you are but will save you alot of money.
I have never installed the multi heat setting ones so I don't know about them.
I have never taken pictures of me doing this so Cant help you with that. Maybe next time!!!!!!!!!!!!!1