[noppid]

The only thing I recall changing for newer php versions is the includes in the index.php. They are old and call files with the file URL. Change the includes to server absolute paths.
ie. "/home/sitename/public_html/forums/archives/header.php" Instead of...
"http://www.sitename.com/forums/archives/header.php"

For online locations we use this code with this hack in online.php...

     // is the user in the archives hack
     $myfind='/\/forums\/archives/';  
      if( preg_match($myfind,$userinfo[location])){
	$userinfo[where] = "Browsing the <A href=\"http://www.lakecs.com/forums/archives/\">Archives</A>";
      }
     //  END is the user in the archives hack

This is placed at approx line 285 at the end of the switch statments default code. It works for us. It's not tested. It's not a released add-on hack.