Every other item class

How would I make it so every other item has a different class. For example:

<li class="brown">link</li>
<li>link</li>
<li class="brown">link</li>
<li>link</li>

Thanks.

Wayfinder 2.5 beta can do this: http://modxcms.com/forums/index.php/topic,33904.0.html or those patches: http://modxcms.com/forums/index.php/topic,31895.msg193726.html#msg193726