jQuery(document).ready( function($) {
  jQuery('#mc_submit_type').val('js');
  var options = { url: mc_ajax_url,
    success:   mc_success,
	beforeSubmit: mc_beforeForm
  };
  //jQuery('#mc_signup_form').ajaxForm(options); 
});

function mc_beforeForm(){
    jQuery('#mc_signup_submit').attr("disabled","disabled");
}
function mc_success(data){
    jQuery('#mc_signup_submit').attr("disabled","");
    jQuery('#mc_message').html(data);
}