Well, I got keen and set to, fitting the cruise control stalk and all of the wiring back to the ECU (on these cars it's in the NS inner wing). I had already worked out that my car wasn't wired for CC... anywhere!
I have the wiring diagrams, and bought a spare ECU and part loom from the scrappy to remove the terminals I needed from, so at the start of the job I had everything I needed to hand.
First job was to remove the steering wheel cowling and instruments, I also removed the centre panel from the dash so I could fit a multi info display instead of the triple info display. (saves time doing both together).
So... for Cruise control, I needed to take three wires to the ECU, from the stalk. The fourth wire (black) picked up an ignition live feed from the instruments. The MID only required one extra connection to the ECU (fuel usage signal) and so a length of 4 core signal cable was routed through the unused grommet next to the brake servo (throttle cable isn't fitted to these).
I had already enabled cruise control in the ECU software via Tech2, so this should almost have been plug and play.
HOWEVER... the ECU continuously thinks the 'O' button is pressed, so CC is effectively disabled. I've checked my wiring twice and even replaced the stalk, after testing it independently.
Does anyone know if it was possible to have cruise control from the factory on the ECO4 models, or any 1.7 CDTI mk4? if I get it working I'll post up a how to, as the work I did wasn't that hard.