[Webtest] posting forms with Spring

[Lisa Crispin]

When using Spring for UI development, it uses the same controller for the
get and the post of a form (eg, SimpleFormController).  When the form is
posted, Spring reattaches the parameters from the get to the posted
request.  Is there any way to simulate this behavior in WebTest?  I.E., when
a submit button is clicked, specify additional parameters for the posted
request.
thanks
Lisa