TOPIC: Question: Best way to install "kill switch" ?

I'd like to install a "kill switch" directly on the engine to replace the key type dash shut down. This is a 1960 40hp Johnson with electric start, but no generator. I've already wired a start
button and short cables on the engine, and that works fine. I don't intend to utilize a "control box" or any dash wiring or any other electrical - mainly because I don't have them. For power to the starter, I intend to utilize a "jumper box" and/or possibly, a garden tractor battery. I need something to stop the engine from idle (similiar to what was on the old dirt bikes)..
What is the "cut-out" switch function?? (I see this item in the parts catalog and find it on the side of the engine, but the two wires mounted on the center post go nowhere and the wire on the side post goes up under the flywheel??
I can't follow the wiring diagram in the Sealoc manual, so could use some advice...
Can this "cut-out" switch be utilized as a "kill switch"? If so, how wired? If not,what is the best way to wire one?
Thanks, Ed
1957 Glasspar "Club Lido" 7 1960 40hp Johnson "big-twin"

Best place to mount is on the front of the bottom pan - just behind where the steering cable attaches to the engine. If there is a factory drilled hole in the bottom pan - go ahead and use that hole. If not, you will have to find a good location to put one. Use a heavy duty MOMENTARY push switch for this. It needs to be normally open - just like your starter button. Find the 2 wires that go to the magneto - if there is a plug on the side of the lower pan - they probably end there at the plug. Connect the wires to the switch (one wire per side of the switch) When the button is pressed and held in - it shorts the two wires together and stops the engine. That's all there is to it.