hmm, i can help you on the index part, which should be quite equivalent to the forumdisplay part:
open index.php and find:
PHP Code:
$forummoderators=$DB_site->query('SELECT user.userid,user.username,moderator.forumid
FROM moderator
LEFT JOIN user
ON (moderator.userid=user.userid)
ORDER BY user.username');
and change it into:
PHP Code:
$forummoderators=$DB_site->query('SELECT user.userid,user.username,moderator.forumid
FROM moderator
LEFT JOIN user
ON (moderator.userid=user.userid)
WHERE user.usergroupid NOT IN (xx, yy, zz)
ORDER BY user.username');
and then just replace xx, yy, zz with the usergroupid's of the groups you don't want to show up in the listing