i got it from these guys
http://www.bridgwater-electronics.co.uk/
It requires splicing into the pedal pot wiring loom and there is a wire connection to the brake pedal switch, and you have to connect it up to the speed signal which is conveniently in the stereo wiring loom at the back. I got a stalk control and mounted it to the plastic cover around the top of the steering column. i must say it it quite unobtrusive and seems to work quite well. I think on a manual you also need a connection to the clutch and/or gear lever, my car is an auto so it was pretty simple.
On a cautionary note i have had more CEL problems from the pedal pot since fitting this, but i am not sure this is directly related to the cruise control, but it might be. The problem is I also remove and replace the pedal sensor in my car every week or so because i am still making these things, so my car is not a great example! So the errors are more likely the sensor as i am running one that does not meet its spec, because i sold all the others
. I will fit a good sensor within a week and see if it settles down.