este es el codigo...
<div id="slideshowContainer" class="slideshowContainer"></div>
<div id="thumbnails" style="display:none;">
<? foreach($imagenes as $imagen):?>
<a href="/img/galerias/<?=$imagen['img']?>" class="slideshowThumbnail"><img src="/img/galerias/<?=$imagen['img']?>" border="0" alt="image"/></a>
<? endforeach;?>
</div>
<script type="text/javascript">
window.addEvent('domready',function(){
var obj = {
wait: 3000,
effect: 'fade',
duration: 1000,
loop: true,
thumbnails: true,
backgroundSlider: true
}
show = new SlideShow('slideshowContainer','slideshowThumbnail ',obj);
show.play();
});
</script>