Badinfo,
I found the info you wanted,
Snip the wire to the injection system engine temp sensor B11/2 (rear of cylinder head on left side) - it is a green wire with a red stripe. Then splice in a 470-ohm resistor in series. This has the effect of telling the injection computer to enrich the mixture just a bit at idle. Putting a switch in parallel with the resistor will give the adjustabillity you described previously. I leave mine resisted constant. It dosn't seem to effect emmission controls or the cat.
also the engine controls are driver adaptive so, constantly switching it on and off may fool the controler into operating rong.
Either way have fun experimenting!
Adam

Thank Adam for that... he is the man you know...