Wanted to do the same. Came looking for this answer sort of.
My "hack was to just do JS mouseover's. I didn't edit the Spry
tabbed panels .js. Rather included them in the code ( which I was
trying to avoid seeing as I had a nice pretty CSS to do my hovers.
So I have messy Javascript code that isn't pretty. But it works!
Let me know if you find a "cleaner solution". But until then, this
worked for me. Below is an example that allowed me to create my own
tabbed panels. Hope that helps.
<div id="TabbedPanels1" class="TabbedPanels">
<ul class="TabbedPanelsTabGroup">
<li class="TabbedPanelsTab" tabindex="0"><div
id="box1"><img src="Image1.jpg" alt="" name="Image1"
width="268" height="138" id="Image1"
onMouseOver="MM_swapImage('Image1','','RolloverImage.jpg',1)"
onMouseOut="MM_swapImgRestore()"></div>
</li>