How to add an extra class to secondary links

Hi Drupal Ninjas!

This problem is driving me crazy! I needed Drupal 6 for it's Multilanguage functions which where not good enough in Drupal 5.

The problem:

I have a right sidebar with my secondary links in a block. My secondary links contain 3 links.
I need these 3 links to have a different icons in front of the link. Was trying to accomplish this by adding an extra css class to the list item formed by Drupal.

Default Output

<ul class="menu">
  <li class="leaf first"><a href="http://#" title="title">button</a></li>
  <li class="leaf"><a href="http://#" title="title">button</a></li>
  <li class="leaf last"><a href="http://#" title="title">button</a></li>
</ul>

But....... I can't hook the list item for only my secondary menu block. When I hook the theme_menu_item_link(), I can add and extra class, but this will be used by all menu items.
This function don't receive a menu id, and I can't make an exeption within this function.

What I really would like to accomplish is:

<ul class="menu">
  <li class="leaf first 1"><a href="http://#" title="title">button</a></li>
  <li class="leaf 2"><a href="http://#" title="title">button</a></li>
  <li class="leaf last 3"><a href="http://#" title="title">button</a></li>
</ul>

Just add numbers to the link class of my secondary links to add an icon in the stylesheet li property.

I tried to make a view, but view links also use the menu_item_link function, so that's not helping me.

Does anybody have an idea how I can accomplish this?
Thanks!