If aftermarket, just buy a kit and follow the directions.
If stock, then quite a bit. The wiring harnesses for the switches are *not* in the console for non-equipped cars, so you'd need the elements, all the wiring, the ashtray cover with the cutouts, and the switches. The elements you'd want to buy new. The rest would most likely have to be procured from a junkyard. Installation is best done with seat out of the car. Get hog ring pliers and a bag of hog rings and go to town!
Unless you're talking about *moving* the elements from your 01 to the 02, in which case just pull and swap the associated bits. I'd recommend getting the wiring diagrams book so you can make sure you get all the harness.