Three torx screws under the steering column cover holding the two pieces snapped together, and one more holding the lower half to the column. Three tamper-proof torx screws holding the ignition switch to the column. When it's still in place, there will be a small silver roll pin pointing toward your face. Push that roll pin all the way in, (about 3/16"), and turn the key to "run" and the cylinder will pop out. When installing the cylinder into the new switch, turning it to "crank" will push the roll pin back out to lock the cylinder in place.
Be sure to check the electrical connector for signs of overheated terminals. They can be cut out of the plastic connector body and replaced individually.