If you cannot get it to be the logo a easier way to get it up is use HTML image code and paste it in your site description.
The only thing is if you do put it in for the site description, from first glance, it looks like the default templet logo is where the site description should be.
But anyways, if you choose a different templet use this HTML code.
<IMG SRC="PICTURE URL HERE" WIDTH="41" HEIGHT="41" BORDER="0" ALT="a sentence about your web site">