WordPress MU

When listing your page links in a theme, how can I force it to restructure the links to fit this format...

<a class="page-item" href="(whatever link is for the WPpage)"><img src="images/link.png" alt="Link" /><span>(The Name of the PAGE)</span></a>

A normal link on my site looks like this:
<li class="page_item page-item-2"><a href="http://blog.dearbornschools.org/about/" title="About">About</a></li>

I guess what I am asking is can I remove the

<li>, Add <a href="link">, then Add <img src="images/link.png" alt="Link" />, then add <span>(Title of Page)</span> 

I think I have seen this done in function.php.  ANyone care to help get me going?

Thanks,
Chris

Why not do it through CSS. Give the navigation li a background image and position it how you want.

Well, I am designing a theme and using a navigation that requires this type of formatting to display properly. Any suggestions?

I guess I am looking for the hook that will call the link for the page and then the title of the page for. Then in functions.php I can format how the links should appear.

So you want to replace a page link with an image?

yeah, it's done via css.