I imagine it’d be possible, but it would need to be cross-browser compatible which might be very difficult to achieve, whereas current js solutions will work on pretty much any browser. I don’t think from a page loading time point of view it’d be worth the effort, as with sliders the part that takes longest to load is the images themselves – not the script. For example I use nivo slider quite a lot, and the JS file is only 6.9kb.
there are some css-only slideshow solutions that do work cross-browser, but they are very limited in functionality/format. check out http://www.cssplay.co.uk/menu/ if you want to see more. this guy’s been making css-only slideshows since 2006.