Found this and yes, it's a splice harness job, unless you get a piggyback harness thing like the guy did in this thread.
http://www.gtr.co.uk/forum/83619-how-in ... encer.html
I think most of what you need was covered in this thread, although I think that the actual UK installation guide was only available from Big Phil if you contacted him directly. Not possible now, I'm afraid, unless anyone else on here has kept a copy of the guide.
viewtopic.php?f=37&t=9086&hilit=KHS+speed+defencer&start=15