After reading this discussion I whipped up a little Javascript module:
http://commons.wikimedia.org/wiki/User:Dschwen/slideshow.js
Activate it by putting:
// [[User:Dschwen/slideshow.js]] - please include this line document.write('<script type="text/javascript" src="' + 'http://commons.wikimedia.org/w/index.php?title=User:Dschwen/slideshow.js' + '&action=raw&ctype=text/javascript&dontcountme=s"></script>');
into your monobook.js
It is far from perfect, but it's a start. I still want to make the Slideshow button to auto-hide, make the time between slides confugurable, add manual advance and back buttons. etc. Take it as a proof of concept. tested on Firefox and Konqueror. Best, Daniel