Since I needed to look these up, decided to put them where I can find them.
When using AJAX and POST, need to put the normal posted content into a file, test.txt in this case and then send the data to the server using either curl (for one off checking the result) and apache bench (too see how fast it can respond)
curl -d @test.txt http://local.site.com/ajax/post/url
ab -p test.txt -T "application/x-www-form-urlencoded" -H "X-Requested-With: XMLHttpRequest" -c 1 -n 10 http://local.site.com/ajax/post/url
For ab, c is for concurrency, n is for number of requests. Need to check the expected document response length to be sure that are not getting back a 200 with the wrong values. T sets the content type, H adds headers to the HTTP request.