Huge request (probably)

I've done this on my website (in my sig)
This should be pretty simple for you to do and i'll tell you how right now (as well as I can not knowing the script)
Anyway. If you have a single header file for your someryc throughout all the pages - then on the comments page, at the top, put:
<?define('TURN_OFF_MAINT', 1);
define('QUIET_VISIT', 0);
define('PUN_ROOT', 'mboard/');
require PUN_ROOT.'include/common.php';
require_once PUN_ROOT.'include/parser.php';
?>

Sorry  Change mboard/ to the relative link to your forum from the page.
Then, where the form is for the comments you will want to add an if else statement like this:
<?
if ($pun_user['g_id'] == PUN_GUEST){
    echo"You must be registered to post comments<br><bR><br>";
}else{
comment form code & the code that sends it to the database?
}

It's that simple. If where the script runs to insert into the database is on a different page, then add the first thing I posted again at the top of that page. then, immedietly after add:
if ($pun_user['g_id'] == PUN_GUEST) message($lang_common['No permission']);

So if they're a guest, they won't be able to view the page.

Hope that helps. Peace.

why not install akismet to handle the comment spam?

Try this: http://www.punres.org/viewtopic.php?id=1850 - it's what I'm using on one of my forums.