you want to run new wiring and new switch? (clarification)
One wire (should be fused) to the battery, other end to pos lead of fog light.
one wire to a ground, then to one side of switch, 3rd wire from switch to other lead of foglight.
You CAN switch ground or power. I prefer to switch ground, so all the power isn't going through the switch...dunno why, but it sounds better to me.
I'm tired and only 40% of my brain is functioning right now so if this doesn't make sense you'll know why...