[Freesteyelz]

Well, there are several ways to do it but for fluid width try this:

In spacer_open template find:

<else />
<div align="center">
 <div class="page" style="width:$stylevar[outerdivwidth]; text-align:$stylevar[left]">

Add after:

<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
                <td width="20px" nowrap="nowrap" style="background:#000000"></td>
                <td>

Save. Then go to spacer_close template and find:

<else />
  </div>

Add after:

                </td>
                <td width="20px" nowrap="nowrap" style="background:#000000"></td>
</tr>
</table>

Change "width="20px" to whatever you want. Also change the background value to:

background:#000000 url(path/to/background/image/.gif) repeat-y top left

Change the .gif to whatever image extension you're using.

Chances are that you'll have extra outborder width (space between border images and forum frame) so go to StyleVars and the 3rd option "Outer Border Width (pixels)" change the value to something smaller.

I tested it and it should work but you never know. Let me know how it goes.