[fw-mvc] Setting form elements properties on the fly

Hello list,

I'm trying to modify some form elements before showing the form ; is it possible to do this with Zend_Form.

Here's the scenario :

$form = new MyNewBlogPost():
if( User == "RegularPoster")
   add 1 to the hidden field SuperUser...
          
   I'm not sure how to do that.

Thanks
JA.