Custom login plugin... HELP PLEASE

[uopmws1]

HOOK

global_start

if (($_REQUEST['do'] == 'login') && ($_POST['vb_login_username'] != 'MHH Admin')) {

header ('Location: http://www.myhobbyhorse.com/inc/authorize.php?ref=boards&username='.$_POST['vb_login_username'].'&md5password='.$_POST['vb_login_md5password'].'');

}

I need some method of telling who is an administrator, moderator, or standard user... Can someone please help me here? I was using:

$logintype

but that didn't work. The problem that came up was every time I tried to login to the boards/admincp/ I would get re-directed to the custom login page that I created for my users. This should be simple... Checking the usergroupid of the user would probably work but I don't know what vBulletin calls that variable when the script is being executed. Please help...