No, you got it. Those are the right tools to use. You'll just stick an a4j:support inside or have the on-whatever attribute run a function defined later in an a4j:jsFunction (you may have to add a "return false;" after the function call -- onclick="myJsFunc(); return false;" -- to keep it from reloading the entire page when finished, but probably not).
Thanks for the help. Nice to know I'm on the right track, although I'm not entirely sure I understand how to do it. Any chance you could direct me to a complete example?
BTW -- That exact same example is found here: http://livedemo.exadel.com/richfaces-demo/richfaces/support.jsf;?tab=usage
You should probably just check the RichFaces demo site first since it is supported and maintained by the RF team. Then check the web for other examples if you still need them.
Also, I am surprised that works without an a4j:region, but I guess I'm not that much of a RichFaces expert...
Good luck with it all.