Pull the tumbler out. There is probably the pin you push in with an awl directly underneath the tumbler. You'll probably have to remove the trim around the steering wheel column. Typically the key has to be in the RUN position (truck not on) for it to pull out.
Remove the key from the tumbler and then reinsert it. The tab that pops up will be the one that you want to cover with tape or any other non-conducting material.
I am not sure what wire it is or what else it would affect on that vehicle. I know that with older vehicles it was pretty obvious which wire it was when you get under there and that all it did was control the key in chime.
You might try talking to a dealer to see if they can get you a wiring diagram.