jQuery SerialScroll: Add class to active item

I'm using Ariel Flesler's serialScroll script and would like to add a class to the active, or highlighted item so I can style it with CSS. Reading the documentation I discovered the notify trigger, but I'm not sure how / if it could be used to accomplish this.

This is my code:

jQuery

jQuery(function( $ ){

    $('#slideshow').serialScroll({
        items:'li',
        prev:'#screen2 a.prev',
        next:'#screen2 a.next',
        offset:-180,
        start: 0,
        duration:1200,
        force:true,
        stop:true,
        lock:false,
        cycle:false,
        jump: true
    });

});

HTML

    <div id="screen2">
    <div id="buttons">
        <a class="prev" href="#">Previous</a>
        <a class="next" href="#">Next</a>
        <br class="clear" />
    </div>
    <div id="slideshow">
        <ul>
            <li><img src="http://www.stockvault.net/data/s/113497.jpg" /></li>
            <li><img src="http://www.stockvault.net/data/s/100177.jpg" /></li>
            <li><img src="http://www.stockvault.net/data/s/101916.jpg" /></li>
            <li><img src="http://www.dreamstime.com/animal-steps-in-snow-thumb12853223.jpg" /></li>
            <li><img src="http://www.dreamstime.com/animal-eggs-thumb15876342.jpg" /></li>
            <li><img src="http://www.dreamstime.com/animal-cat-thumb15385101.jpg" /></li>
            <li><img src="http://www.dreamstime.com/green-nature-thumb596309.jpg" /></li>
            <li><img src="http://www.dreamstime.com/office-in-nature-thumb3256171.jpg" /></li>
            <li><img src="http://www.dreamstime.com/nature-tree-thumb16030502.jpg" /></li>
            <li><img src="http://www.dreamstime.com/gift-of-the-nature-thumb15977958.jpg" /></li>
            <li><img src="http://www.dreamstime.com/nature-abstract-thumb3615419.jpg" /></li>
            <li><img src="http://www.dreamstime.com/nature-path-in-forest-with-sunshine-thumb8241130.jpg" /></li>
            <li><img src="http://www.dreamstime.com/nature-walk-thumb8436665.jpg" /></li>
            <li><img src="http://www.dreamstime.com/save-the-nature-thumb15696583.jpg" /></li>
        </ul>
    </div>
</div>

Am I misunderstanding the function of the notify trigger? And if so, is there any alternate ways of accomplishing what I'm after?

From the plugin example page, here's how onBefore is being used:

onBefore:function( e, elem, $pane, $items, pos ){
    /**
    * 'this' is the triggered element 
    * e is the event object
    * elem is the element we'll be scrolling to
    * $pane is the element being scrolled
    * $items is the items collection at this moment
    * pos is the position of elem in the collection
    * if it returns false, the event will be ignored
    */
    //those arguments with a $ are jqueryfied, elem isn't.
}

in that function, you can add your active class, and use the onAfter function to remove the class from the previous element.