So if anyone is interested in exactly how to put a switch in (I've gotten a PM asking for clarification).
Buy a simple SPST (single pole single switch) toggle switch from Radio Shack or wherever. You can also use a rocker, or a push button. I wouldn't recommend a lighted one because I'm not sure where to find a 12V down there, and also because some of those switches only have three terminals. A +V, a GND, and an ACC. So in order to get light, you have to tie the thing you want to switch into +12V, which isn't what we want. If you can find a proper GND and 12V source down there, and get a 4 terminal SPST switch, feel free to get a lit switch, although you'll be putting it in an invisible place anyway.
Unplug the sensor plug as shown earlier. Cut the tubing around the wires back some so you can get at the wires. Pick a wire from the sensor plug, and cut it about halfway between the sensor and the edge of where you can see it come out of the tubing. It probably doesn't matter what wire you pick. I tested them all, and most are 0V DC. One is .3 V, probably the power for the chips. One is ground, and the rest are probably signal. I picked the power one, but it doesn't matter.
Get a couple feet of wire (18-20 AWG stranded is probably best, approximate match for the sensor wires). Cut it in half and strip each end. Strip the two ends of the sensor wire that you cut.
Take out the third screw and completely remove the bottom piece of plastic from the steering column. Drill a hole in the bottom the size necessary for your switch that you've bought. Make sure you don't drill it in the inset where the tilt handle goes, unless your switch is short enough to clear it. Before you install the switch, solder one end of each of the long wires that you cut to the terminals on the switch. Then install the switch in the plastic. Heatshrink those connections (or electrical tape if you can't heatshrink, but I'd really recommend heatshrink, electrical tape gets nasty after a while). Then slide heatshrink on the long wires and solder one end of each to the cut ends of the sensor wires. Slide the heatshrink over the connections and solder. If 1 foot is gonna be too long, you can cut them to length before you solder, I didn't measure, I just used some pieces of wire I had. Plug the sensor back in, turn the ignition on and see if your switch works. With the toggle off you'll have no SWAS so the lights will be on. If you switch it ON after it has been OFF, the car will still think it has a problem until you turn the car on/off again.
If it's working, put the plastic cover back on the steering column, and tighten it up. You're done.
Simple.