"Dumb," static authentication?

Hi, all.  (First and foremost, I hope this is the right list; I usually
hesitate to e-mail "developers'" lists with usage questions, but that
seemed to be how it's done here, so...)

I'm about to set up a captive portal for my company -- specifically, for
visitors/contractors.  We don't want anything over-the-top; all we need is
for ONE static password to be implemented, which we'll change on a (say)
weekly basis.  Basically, we're just looking to discourage the casual
peruser.  Since the WAP in question is outside our firewall, it's not like
we're worried about security -- we just don't want to be an open access
point.  However, the docs that I've found all seem to imply RADIUS or an
SQL database, etc.  Is there any way to just do a query against a local
text file, or PAM, or something?

Thanks!

-Ken D'Ambrosio