It is actually quite doable - see this article on CSS3 rotation and filters in Internet Explorer, and also search for the CSS3 Transform property - http://www.useragentman.com/blog/2010/04/05/cross-browser-animated-css-transforms-even-in-ie/
Although I would state right here and then that whatever purpose you might have use for a Javascript loading bar be 90% of the time it can't be good. If your page is so big that it'll require a loading bar then you really really should consider a redesign/rewriting of your code and design for the site. The same would be if you want animation just for the sake of animation.
But I'm afraid I might have said a little too much - don't let that discourage you from having a look at a very interesting technique, or from using it on whatever you deem necessary. If you need more help just drop a comment on this question.