I did this the other week took ten minutes to do one wire in the drivers seat. Got a new cable short if it goes to the outerside of the car longer if the inner side.
1 Firstly you need to unclip the material that is on the upper seat back. To do this flip the seat foward and sit on the back seat. Look at the seam on the base of the upper part of the drivers seat, there are about five upholsters copper clips. These need to be bent open to allow the cloth to be freed. One open you can move the material up the seat a little.
2 Remove the old wire which will prob stab you in the arm!! The you need to look at the cable routing. Easiest way is to clip the cable into the tilt mech on the side of the seat FIRST. The down inside the seat, through a little rubber O attached to the metal. The the cable goes directly across the seat, then down through another O. Throught the metal and clips into the onter retaining hole. The just do up the material again. But check the seat works before you do this so you don't have to do it twice.
I didnt need to take the seat out, just thought it took more time. also got a new cable from a scrap yard. I accidently fell into the old seat with a stanley knife which allowed me to see the cable routing. Which would make the above instructions make more sense.
If you need some pictures let me know
Tim