Unfortunately not easily. Even if the anchor links were embedded using Ajax and from an external file, you would still need to add an empty DIV on each of the affected pages and tell the script to insert the anchor link inside that DIV- in other words, modification to each page would still be necessary.
Since each anchor link contains a certain CSS class and rel attribute, such as:
your best bet should be just to target either that class or rel attribute inside your external CSS file to affect its font.
<p><a href="http://www.dynamicdrive.com" class="menuanchorclass" rel="anylinkmenu1">Default Example</a></p>