The cruise control system fitted to some versions of the KV6 was an factory fit optional extra (R45 2.0 conny was standard), it was never offered on the MG ZS180.
I documented my attempt to fit it to my mk1 over on ZScentral
http://www.zscentral.com/phpbb/cruis...rol-t8163.html
but, like Sam, I got stumped on the wiring.
Or it might be that the ZT KV6 throttle body for cruise has a different part number to the non cruise throttle body.
The after market cruise control offered by Rover was a standard kit from Rostra, I bought a kit direct from the USA and fitted it to my MGF where it works well.
I have fitted the O/E style steering wheel controls and started to work out the wiring.
There is no reason this couldn't be made to work on the KV6.
http://www.rostra.com/universal-afte...-by-rostra.php