From what I see, FSCommand would be the appropriate actionscript to use. You would create a javascript function, say, PHP_Post, that takes each input as a value. Then you'd use FSCommand("PHP_Post", "VALUES"), parse it through the script, and send it to the script.
As for the javascript itself, W3 should have enough information to cobble together something that works. Within, I'd simply use a redirect with something like:
location.replace("http://the.page.here/the.php?arg1=".$arg1......)
Just an idea.