You could integrate any additional client side widgets to your application but should add server side processing/synchronization for the widgets on your own.
Hi Eurokey, don't know if this answer your question, but RichFace has already a JS library attacht. Please have a short look:
Maybe the documentation or wiki regarding jQuery can help you to solve your problem with your own JS-Component?
Or you just try it.....and play a litte bit around with your component?