hmm.. cursory googlage makes it seem as though there's some master script (rc.S) that in turn invokes rc.pcmcia BEFORE entering any runlevels. if that's true, then if the rc.pcmcia script is missing, as you say, then rc.S would keep trying to run it without success. can't imagine where the script would have gone though. unfortunately, i couldn't immediately find an example of slackware init scripts to read through on google. i might consider copying this post into the slackware forum, though, 'cause most of us lesser mortals are reared on System V init scripts and haven't got much of a sense of how slack boots
i still think your ultimate goal should be killing the pcmcia service, since you're not using it anyway.
hope you find someone more helpful than me...