I made an updated version of the s5 package, which uses now a .vuh file in www/admin/. This seems to work quite well in combination with the .vuh file in www/. Together with Günter Ernst, i fixed a small bug in the standard style, which made it impossible to use the slide selection in the right lower corner on IE7 (problem with event bubbling). On IE, it is not perfect (the sizes and positioning of the footer on IE is not correct, but all css), but at least firefox and Safari work quite well.
The updated xowiki-s5 package can be downloaded from http://media.wu-wien.ac.at/download/s5-0.2.apm