Using base_url DOESN'T work and was generating the same crossdomain request. That is what I was using originally but I just put in the whole URL in my post to be clear. Because it's part of Code Igniter I really was expecting this to work.
I didn't see anything in the online documentation about having to use relative URLs and in the examples that come with CJAX for CI there is no Code Igniter controller file that shows how to link to an AJAX request. Maybe this is obvious for AJAX developers but I spent a week pulling my hair out.
One included file like below would have made things very clear:
------------
<?php
class Cjaxtest extends CI_Controller {
public function test()
{
require_once(FCPATH.'ajaxfw.php');