Yah, I don't understand why people make things so complicated once Javascript gets involved. Just inspect the XHR traffic to your browser ("Network" tab in Web Inspector, Firebug, etc) as you update the information on the page. You'll quickly discover what are essentially undocumented APIs returning the data used to generate the page. You don't need to use or even read through the Javascript that's calling them, you just need to figure out what parameters and cookies are being sent, and tweak those as you wish.
You might have to spoof the Referer header so that it thinks the request is still coming from their website.
The answer is HttpFox. It records all http-requests.
1. Start recording
2. Do some action that causes data to be fetched
3. Stop recording.
You will find the url, the returned data, and a nice table of get and post-variables.
https://addons.mozilla.org/en-us/firefox/addon/httpfox/