I've created a modification that allows this. I haven't documented it yet and there are a number of files needed plus a few that needed modifications added.
The simplest way to add a column staticly is to open a two column table after the navigation bar and close it before the footer.
At the end of your navigation bar templates (ubbt_registerednav.tmpl,ubbt_unregisterednav.tmpl) add:
<table width="100%" border="0" cellpading="0" cellspacing="0">
<tr>
<td align="center" valign="top" width="22%">
<!-- left panel content goes here -->
</td>
<td align="center" valign="top">
At the begining of your ubbt_footer.tmpl add:
</td>
</tr>
</table>
This will place a left hand column into your forum.
