I did my mk3 many moons ago but it was really very easy unlike my mk4 loom I fitted in my current car was a lot more fiddly.I just found this quick guide on the net hope it helps..
1. First remove the plastic pieces to the left from the clocks, where the heater switch sits or blanks, if you don't have heated leather. Then remove the airbag light plastic to the right from the clocks, as well as the headlight switch. Simply use a flat screwdriver to carefully push out the airbag plastic, and the headlight switch comes out, when you push on a little "thingy" on the top right corner that holds it in place. Disconnect the wires.
2. Now you will see 2 screws on each side, which hold the black plastic piece that is covering the clocks. Undo them, and again using a flat screwdriver, push it out from different angles.
3. Finally we got up to the clocks, which are holded by 2 a bit smaller screws. Undo them, and turn the clocks down, so they are facing the steering colomn. Pull them towards you, then disconnect the multiplug, and take them out (a bit tricky, but not impossible)
4. It's time to get the heater wiring connected. When you remove the clocks, you will see there's a multiplug block in different colors (grey/yellow/green/blue), located just behind the headlight switch, that we've removed. Simply plug in the wires from the heater seats into their matching color blocks (I had grey and green + brown), but the brown one goes to the block that is attached to the right corner of the dash, a bit further right from the other colors.
Everything will become obvious, when you remove the clocks. Oh, make sure that you get in the switch wire in its place, before you put the clocks back on. When everything's connected you should have, the switch wire to the left, where the switch sits, the grey/green/brown wires plugged in their relevant blocks, and the seater plugs hanging out from the bottom BEHIND the dash.
That multiplug block was down by my fusebox on my mk3 just have a look round for it but once youve found that its easy then you just need to run the heated seat loom sections under you carpets from the drivers side across.
