Integrating thickbox and Drupal forms

I have a Drupal form that I'd like to add a "preview" button to. When this button is selected a thick box would appear with the form fields listed and themed. I've searched through the Drupal and Thickbox fourms, but cannot seem to get it all working.

1) What do I need for the button - something like this?

   $form['submit'] = array('#type' => 'submit', '#value' => 'Submit');
   $form['button'] = array(
    '#type' => 'submit', 
    '#value' => 'Preview',
    '#attributes' => array(
      'class' => 'thickbox', 
      'action' => '/test.php?KeepThis=true&height=400&width=600', 
      'target' => '/test.php?KeepThis=true&height=400&width=600'),
    );

2) And for the test.php file - something like this?

   print_r($_POST);

3) And finally - a change to thickbox to also activate on submit buttons (I found this code here: http://codylindley.com/thickboxforum/comments.php?DiscussionID=408&page=... )

function TB_init(){
$("form.thickbox").submit(function(){
var t = this.title || this.name || null;
var g = this.rel || false;
TB_show(t,this.action,g);
this.blur();
return true;
});

$("a.thickbox").click(function(event){
// stop default behaviour
event.preventDefault();
// remove click border
this.blur();

// get caption: either title or name attribute
var caption = this.title || this.name || "";

// get rel attribute for image groups
var group = this.rel || false;

// display the box for the elements href
TB_show(caption, this.href, group);
});
}

With this setup - my page behaves as if I had selected the "submit" button.

Cheers, Jason