What I'm reading is that you don't want to bother with a switch, you just want the fogs to come on when the ignition is on, and off when it isn't, correct?
1. Use a relay. There isn't really anything suitable for direct power use, but there may be a few things that can you can use a relay from.
The tach signal (the neg terminal on the igniter, also avaolable at the diagnostic plug) only has a positive signal at all when the ignition is firing. A diode and a capacitor would smooth this out to be a good enough signal for a relay. No ignition, no fog lights. This would mean that the fog lights are on only when the engine is actually running, and not just when the ignition switch is on.
I have mine wired to an ignition power source in the dash, going to the factory fog light switch, so I can switch them off if I want, but then I'm not all that bothered by running yet another wire to my dashboard.