I used this code to add attribute to form:
var $j = jQuery.noConflict(true);
$j(document).ready(function(){
$j( "form" ).attr( "onsubmit", "if(submitting) {alert('The form is being submitted, please wait a moment...');button_save_close.disabled = true;return false;} else if(checkForm(this)) {button_save_close.value = 'Submitting form...';submitting = true;return true;} else {return false;}" );
});
But it doesn't work and make that form don't save at all.