Kill switch install help needed

So I moved to a state where I have to have a kill switch on my '93 Nautique. I went and bought one at the local marine dealer. Never installed it last year and thought I might this year so I don’t get a ticket for it. My wifes boss got a $250 for not wearing his last year while cruising around at a wide open idle. I don’t need any extra trouble!

I've since lost the instructions, but they only said some thing about a blue wire in a Merc application anyway. Did a search here but couldn't find anything so far.
The switch I got is Saf-T-Stop:
http://tinyurl.com/5shj4j

So what’s the best way to wire this little bugger up?

Thanks
Britt

Thanks for the diagram Pete.
I did try and install the switch last year.
I just put in in line with the ignition breaker (the power to everything one). Then I found out the the switch is closed when in the down position and open in the up position. I thought that maybe the switch was installed backwards, but just assumed I didn't know what I was doing.
Now it sounds like the switch might be installed upside down in the Saf-T-Stop housing.

Britt