Well if you haven't gotten it yet this is how I did it, in your header template find:
<td align="$stylevar[left]"><a href="$vboptions[forumhome].php$session[sessionurl_q]"><img src="$stylevar[titleimage]" border="0" alt="$vboptions[bbtitle]" /></a></td>
And replace it with:
<td align="$stylevar[left]"><center><a href="$vboptions[forumhome].php$session[sessionurl_q]"><img src="$stylevar[titleimage]" border="0" alt="$vboptions[bbtitle]" /></a></center></td>
All I did was add the <center></center> tags