is it possible in magento to send parameter to controller form?

        $x=987654;
        $url=Mage::helper("adminhtml")->getUrl("/label/setlabel");
        $block->addButton('label', array(
        			                   "label" => "Get Label",
          "onclick" =>"popWin('$url', 'windowname', 'width=400,height=300,scrollbars=yes')"
  
controller file:      			                ));
    class MyCompany_MyModule_Adminhtml_LabelController
    extends Mage_Adminhtml_Controller_Action
    {
    	public function setlabelAction()
    	    {
    	       echo $x;//is this possible?
    	    }
    
    }

 i have this $x parmeter, is it possible somehow to send it to controller and echo it there?