In my case, I want to change post_params to send dynamic value from input form. I've tried to change settings by set through the swf object. Following code is example I've done:
var swfu = new SWFUpload(settings);
I change settings with this code:
swfu.settings.post_params.my_var = value
Something like this but my_var doesn't send to php script.

PS. I'm not good in English. Sorry, if make you confuse. Thanks in advance.