Here is a quick drawing of the circuit I built. As it's shown, it waits about 6.5 seconds then sends about a 0.5 second pulse to the transistor which pulls the "TCS OFF" line low. If you want to shorten the delay, make the 47uf capacitor or the 120k resistor smaller. 6.5 seconds is long enough for all the dash lights to go out, but you may be more impatient than I am. :) If you look under the dash on the drivers side where the fuse box is, there is a red wire with a white strip coming out of that fuse box. This wire goes hot when the switch is in the "ignition" position. I used one of those splice connector thingys to connect the positive supply of the circuit here. There are 6 connections on the TCS OFF button itself, but only 4 are used and the other 2 have been removed. The 2 farthest from the removed connectors are for the lamp inside the button, and the other 2 are for the button itself. I don't remember what the colors are, but the middle 2 connections are for the button. The wire closest to the removed connectors is ground, connect the circuit ground here. The 2nd wire from the removed connectors is the signal wire, connect the collector of the NPN transistor here. I just tinned the end of the wires coming from the circuit to make them stiff and pushed them into the plug that connects to the button and they seem to be staying in place fine. The button can be removed by reaching up from under the dash and squeezing the clips on top and bottom and the button will pop out. Once you have the button out you'll see what I mean about the connectors, and you might want to double check what I've said, I may be remembering incorrectly, or your button may be different for some reason. I hope this makes sense :)
I don't know the number of the box I used but it's the one that's really small, about the size of your keyless entry remote. All the parts I used were from the Shack. I used a blank PC board and cut it to fit inside the box. You'll have to drill a hole in the middle for the screw that holds the box together. Oh yea, get the smallest capacitors you can find or else you'll never fit them into the box. :) I got one of the 20 piece bargan electrolytic packs so I'd have a few to play with, but you can just get the ones you need. The 0.01uf is a small ceramic disc. Use careful placement on the PC board so you can get all the parts in there and get them connected. You can get one of the bigger boxes if you don't feel like being very intricate. :) The LED and it's 1k current limiting resistor are optional. I put them in so that the LED will light while the 555 is in timing mode. At the end of the time, the LED should go out and your TCS should be off. I figured this would be a handy troubleshooting aid if I had problems with it later. You can also put a switch in the positive supply line so you can turn the whole thing off and leave your TCS on. I want to do this sometime, but I haven't figured where I can put the switch so its not in the way but still easy to get to.
It was a pretty fun project to work on, and not too expensive. Shouldn't cost you more than $20, even at the Shack's inflated prices. :) Plus it's cool to have the TCS off without having to spend extra clock, er brain cycles to actually push the button. :) Sorry for the long winded post, good luck :)