I have searched and searched the internet to find a Cruise Control installation guide and "Sijones" was the only guide I could find. Hope you don't mind Sijones as I'm going to include a few pictures and notes for others
This guide is for the 3 spoke steering wheel with Multi Function, it may differ slightly for other steering wheels.
Some of the pictures have the Cruise Control stalk in them, this is because I took the pictures for the guide after fitting the new stalk!
1. Before disconnecting the battery, start the engine and rotate the steering wheel to remove the two black plugs from the back of the steering wheel followed by the two airbag fastening bolts "T25", be careful not to let the airbag fall out after removing the screws. Then straighten the wheel, turn the engine off and disconnect the battery. (I have the 3 Spoke MFSW)
2. The Image below shows the back off the airbag and the connectors. The Top of the Yellow connector is orange, this pulls backwards towards the camera to release the yellow plug. The black plug just pulls apart. (Some say don't disconnect the airbag for 30 min after disconnection of battery, I did it straight away and had no problems)
3. Then undo the M12 (Multi Spline) bolt, Just remove the bolt, do not pull the steering wheel it will come off, it's not like old style where it was wedged on.
4. Take a good look at the middle, and you will see 2 marks, one on the steering wheel and one on the steering rack. Perhaps take a photo if you can so you have a referance, on mine the steering wheel mark was pretty "spot on" to the rack mark. Once you know, pull the wheel off...
5. Remove the bottom cowelling, to do this you need to remove the adjuster handle underneath (2 x T25 screw) and the other T25 screw that you will see. The top of the Cowell hinges up like a car bonnet so you can gain access to the two front T25 screws (do not disturb slip ring position)
6. Your then looking at the slip ring, now as everyone says to be really careful not to move it etc etc, I used insulation tape and placed that over it to stop any movement.
7. At bottom of the slip ring is a T9 screw, remove it... Now the steering ECU to remove.
Remove the 2 connectors at the back, to do this the main (big black one) one has a plastic clip that's red and with a flat blade is pulled out which allows you then to push a another clip behind down and pull the black plug out, sounds complicated but it's easy when you see it. The other connector is a spring loaded clip, push it away from the ecu and the plug will come out.
8. Now between the main black plug and the small other plug there is a plastic latch, with one hand gently pulling the ecu down, use a finger to find the latch and release (see photo) The first clip is directly above the black connector, you push it in and the back of the steering ECU will drop down
There is another latch to be released from the front (I struggled like hell with this one!) , you can use a 2.3 mm drill bit to push down the hole which should release the second clip (see Photo), Do not try and force the ECU down as you bend the clip and make things worst like I did, I didn't know the construction of the clip but it all becomes clear when you see the ECU removed, so this should be a head start for you guys.
This shows T9 screw and the hole below for the release of second clip (I used 2mm long allen key)
The below pic shows the chamber the 2.3mm drill or allen key comes through to, the clip is shaped like a goal post and should have a plastic leg hanging from the top middle of the goal post crossbar which would be touching my allen key on the left side had i not snapped it off in anger! Again don't try and force it down, the ECU will drop on its own when the clip is properly released. When you push the allen key through it pushes the clip to the left and the ECU should drop.
The ecu should pull downwards off the rack with these 2 clips released.
9. At top of wheel there is 2 clips holding slip ring in place, one at 10 o'clock and the other at 2. Unclip and the slip ring will pull off.
10. Remove the ESP steering sensor at the bottom and put out the way
11. The indicator stalk is held in by a plastic clip at the left back, i used a screwdriver to prise this while pulling the stalk forward away from dash, it seemed like it was being held, but with a little tug it came off.
12. Push new one in place and reverse above, dont forget esp sensor, slip ring on, ECU back in, T9 screw in, Cowelling back on, steering wheel (check alignment with reference point), tighten bolt, airbag and MFSW plugs, screw airbag in and your done!
I did get the ESP error message when restarted car, this went after driving for 2 minutes.
If you need the control wire, it goes to pin 13 on steering main black plug, and pin 4 on a blue connector under dash, the instructions say remove the connector but using pin nose pliers i pushed it into the connector in place, simply because i couldn't for the life of me get the connector out as it's in the most akward place and no room for tools really to undo it...
Big thanks to Sijones