Seam has no built-in mechanism for that and it's a little tricky to get Facelets dynamic. Have a look at the stuff in Seam CVS in examples/wiki/ and how the plugins render their plugin.xhtml dynamically with a Facelets handler. That should get you half way there.
Thanks for your feedback! I didn?t realize it was that complex, but again you smart Seam guys figured a way. ;-)
And regarding Pete Muir?s blog (that I've bookmarked now): I?ll vote for ?Serving up dynamic resources RESTfully?
BTW: The wiki looks great!