[Freesteyelz]

Only this code will go in the Additional CSS Definitions:

img {
  border:0;
  }

This code you'll add in your header template:

<a href="yoursite.com" title="your_site_title_here"><img src="your_image_url_here.gif" alt="" /></a>

Edited: An alternative method is just to replace the vB logo with your custom one. To do that go to StyleVars and the first "Image Path" is for your title image. Just replace your logo with:

your_site_domain/forum/images/misc/vbulletin3_logo_white.gif