How can I configure logins based on PAM /etc/passwd?

I just installed a new gallery2 site and want to configure it to use the PAM authentication for the users on the system as stored by the basic /etc/passwd file. I read a few things about http_auth but I don't get it. Any step-by-step help on how to do this?

Alternatively, I saw an LDAP-to-database populator program. I don't use LDAP and was wondering if there was a similar script to update the gallery user database from the /etc/passwd file?

I do have full access to the server, so I am not limited in that regard.

Thanks, Bruce

Gallery version = 2.3 core 1.3.0
API = Core 7.54, Module 3.9, Theme 2.6, Embed 1.5
PHP version = 5.2.6 apache2handler
Webserver = Apache/2.2.10 (Fedora)
Database = mysqli 5.0.67, lock.system=flock
Toolkits = ArchiveUpload, Exif, Getid3, ImageMagick, LinkItemToolkit, Thumbnail, Gd, Ffmpeg, Dcraw, NetPBM, SquareThumb
Acceleration = none/0, partial/900
Operating system = Linux 2.6.27.9-159.fc10.i686 #1 SMP Tue Dec 16 15:12:04 EST 2008 i686
Default theme = matrix
gettext = enabled
Locale = en_US
Browser = Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.0.5) Gecko/2008120122 Firefox/3.0.5