Killswitch using stock horn button?

Would that be feasable to use? I was thinking maybe I could disable the use of the horn when the car is off and use it as a killswitch if possible. Which is an efficient type of kill, ignition kill of fuel cutoff? How would I be able to wire it? This is for a 94 honda prelude.

Yeah, that was an idea. Disable use of the horn when the car is off to use it as a switch. And then allow it to be functional when the car is on. I have thought about using a conventional switch and then conceal but I like the idea of using the horns=D. I do have two horn buttons. I think I coould disable one of them, but I'd rather have them both fucntional when the car is on.

Any possible wiring schematics?

You could leave the horn wired the way it is now and have it disable the interrupt with the key in the run position. To start the vehicle you would turn the key to the run position, honk the horn, then start the vehicle. You can tie the blue lead shown below into the positive output from the horn relay at the relay or right behind the horn instead of connecting it to a remote turn on lead or power antenna lead.

https://www.the12volt.com/relays/page2.asp#psk

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The only problem with this method is that horn would sound. I have connected 150db airhorns and it will start to annoy my nieghbors in the morning.  

This is basically two of the configurations above. On the bottom left relay, you will need to cut the positive lead going to the horn from the horn relay and connect each end as shown. The rest should be easy to follow. This set up will not let the vehicle start unless you turn the key to the run position, then hit the horn switch. The horn will not sound when you hit the switch until you start the vehicle (apply 12V+ to the motor side of the starter lead). When the ignition is turned off, the horn will not sound with the switch and the vehicle will not start until you repeat the process.

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Thank you so much - going to wire as so=]

Would the configuration change if i wired it as a fuel cutoff?