Ok, open up customer/home.tpl and place this right before the </head> tag:
{literal}
<script type="text/javascript">
<!--
var image1=new Image()
image1. src="skin1/images/scroller images/offer-01.jpg"
var image2=new Image()
image2. src="skin1/images/scroller images/offer-02.jpg"
var image3=new Image()
image3. src="skin1/mages/scroller images/offer-03.jpg"
//-->
</script>
{/literal}
then put this part wherever you want the slideshow to appear:
<img src="skin1/images/scroller images/100048.jpg" name="slide" border="0" width="115" height="56" />
{literal}
<script>
<!--
//variable that will increment through the images
var step=1
function slideit(){
//if browser does not support the image object, exit.
if (!document.images)
return
document.images.slide.src=eval("image"+step+".src" )
if (step<3)
step++
else
step=1
//call function "slideit()" every 2.5 seconds
setTimeout("slideit()",2500)
}
slideit()
//-->
</script>
{/literal}
Usually that would go on customer/main/welcome.tpl if you wanted it to appear on the home page.