From what I see in my Factory Repair Manual for my '99, it looks like you can replace just the membrane switch.
"There should be continuity between the horn switch feed wire and the horn switch ground wire" when depressing center of airbag module trim cover. "If not OK, replace the faulty horn switch. "
However, it doesn't tell HOW to replace it! The diagram shows "locking blocks" top and bottom and "retainer slots" top right and top left. Based on that it looks like it snaps in place. The diagram makes it look like the membrane switch is almost as big as the airbag module.
Ed