AdminCP->|--HTML Templates->Manage HTML->Board Index Page Top
Add the following on top
Code:
<script language='JavaScript' type="text/javascript">
<!--
if (! document.referrer.match("{ibf.script_url}") ) {
window.location = 'http://YOURFORUM.forumer.com/index.php?act=home';
}
//-->
</script>
It should work... good luck