Although I don't plan on using this script because I'm still unsure how it would affect all indexing bots, besides google- though that is obviously the most important- this change should stop it from refreshing when people go to register...
Code:
<if condition="$bbuserinfo['usergroupid'] == 1" AND "THIS_SCRIPT != 'register'">
<meta HTTP-EQUIV="REFRESH" content="X; url=http://www.yourforum.com/register.php">
</if>
That will make sure it doesn't refresh while viewing register.php.