Hi,
The Ajax Helper just provides tcl wrapper scripts to Scriptaculous javascripts. The Scriptaculous javascripts are responsible for making the xmlhttp request and other neat effects.
Yes there are tcl files that accept the xmlhttp request and respond according. These have to be created by you for your application. Ajax Helper does not have a mechanism to manage responses and requests although it is a nice idea. Gustaf's Xotcl-Request-monitor is probably a package that you would want to look into.
You can read about how I used Ajax and Ajax Helper for this demo page in tutorial 2
http://www.solutiongrove.com/blogger/one-entry?entry%5fid=266155
Ham