Creating AJAX post parameters for TT Controller?

[momijizukamori]

I'm in the process of updating /customize/ to move it away from BML and a million widgets, and I've got most of the HTML-y stuff done, but I'm having trouble with the Javascript. The biggest part of this is redoing the AJAX queries, which were previously done in widget-specific ways and passed through a bunch of the Widget class handlers. Working off jQuery, I've gotten as far as getting it to submit a POST request which reaches the controller - but the param formatting is all wrong and missing a bunch of the parameters sent with a TT form POST request. Do we have methods for creating proper POST requests from AJAX?