The way I prefer, on earlier models, is to cut the one wire coming from the key cylinder (not the ignition switch itself!). This tells the chime module that the key is in the switch. Should work in a '98, should be easy to get to (remove the column trim halves), just be sure to tape your cuts.
Edit: I forgot, but on as late as '94 the key-in-switch wire has a single connector about where the column meets the dash- just unplug. Don't cut wires unless you simply enjoy it!