[Freesteyelz]

If you'll settle for a set width instead of set characters than one method is to control the postbit(_legacy) width by using CSS:

  <!-- message -->
  <div id="post_message_$post[postid]" class="msgwidth">$post[message]</div>
  <!-- / message -->

Add the red. Then in Main CSS and at the very bottom Additional CSS add:

.msgwidth {
  width:500px;
  }

Change "500px" to whatever pixel size you want. The above code will only control the message.

If you want the other message contents (e.g., title, attachments, signature...) to confine to the set width then add that class to the relevant "div" tags. Or simply add in red (and don't do the above steps):

 <td class="alt1" id="td_post_$post[postid]">
 <div class="msgwidth">
 <!-- message, attachments, sig -->

And

 <!-- message, attachments, sig -->
 </div>
 </td>