When I posted it it was a guess. Since then I tried it and it seems to work for the forums (I don't see why you'd get it on every forum - I only got it on the forum home page), but you might need another check in there to see it only on the CMS index page, which I don't know how to do offhand.
BTW I put it in headinclude after I read that's where you had it. I just used this:
HTML Code:
<vb:if condition="THIS_SCRIPT == 'vbcms' OR THIS_SCRIPT == 'index'">
<script type="text/javascript">alert("Here");</script>
</vb:if>