I have generally done the 1 wire at a time method. Also be certain that none of the wires are resting directly on the engine when you are done. If you broke the retaining clips that keep this from happening, be sure to pick up some new ones. Also be sure to use dielectric grease when snapping the new wires onto the new plugs.
RE: Cheap Jeep Series - Replacing the Spark Plugs and Wires!