I finally figured out how to do it using curl. The only thing is that to make it simpler, our users only log in with their username without "+southlockportfire.com" after it (just makes it easier to remember). So I have a form where the user inputs their username, current password, and new password (named 'username', 'currentpw', and 'newpass' respectively). And it posts to the following PHP script:
><?php
$path_to_cpform = "http://".$_POST['username']."%2Bsouthlockportfire%2Ecom:".$_POST['currentpw']."@www.southlockportfire.com:2095/dowebmailpasswd.cgi";
$pass_to = "oldpass=".$_POST['currentpw']."&newpass=".$_POST['newpass'];
exec("/usr/bin/curl '".$path_to_cpform."?".$pass_to."'", $reutn_array, $return_var);
unset($PHP_AUTH_USER);
unset($PHP_AUTH_PW);
echo('<meta http-equiv="REFRESH" content="0;URL=http://mail.southlockportfire.com/">');
?>
I'm sure that if you just change "southlockportfire.com" you'll be able to use this script with your domain, too. Let me know if it works for anybody else!
Jonathan
jonathan@enzinnainteractive.com
enzinnaj@southlockportfire.com