ATG Formhandler:Need to set some values before calling the handle method

My requirement is I have a hidden form from where i am calling a handle method. Along with the handle method I am setting success and error url's as hidden values.

    <dsp:form action="blank.jsp" method="post" formid="UNIQUE_FORM_ID">
    <dsp:input bean="FormHandler.commitOrder" type="hidden" value="submit" />
    <dsp:input bean="FormHandler.commitOrderSuccessURL" type="hidden" value="SOME_VALUE" />  
    <dsp:input bean="FormHandler.commitOrderNotReadyURL" type="hidden" value="SOME_VALUE" />  
    </dsp:form>  

I need to set the successurl and errorUrl before calling the handle method.

I tried giving priority, but still its not working.

Thanks, Neenu