This is the code required to use the Custom Select control with jQuery's serialize

• First, add the function below to your code.
  

  	   function repl_val_with_key ( get_string ) {
  	     var new_get_str ="";
  	     $.each(get_string.split('&'), function(k,v) { 
  		 $.each(v.split('='), function (k2, v2) { 
  		    if ( $('input[name="'+v2+'"]') && $('input[name="'+v2+'"]').attr('key') ) {
  			new_get_str += v2+"="+$('input[name="'+v2+'"]').attr('key')+"&"; 
  		    } else {
  			new_get_str += v2+"="+$('input[name="'+v2+'"]').val()+"&";
  		    }  
  		    return false;
  		  });        
  	       });        
  	      return new_get_str.slice(0, -1);
  	   }
  	  

• Then, pass your serialize call as a parameter like this:
  

            var new_get_str = repl_val_with_key ( $('form#tst').serialize() );