Puoi eseguire i vari steps solo altermine del singolo step, tipo :

codice:
$("#slide_hidden").animate({'width':'0px'},1000,function(){
	 $.ajax({
		type: "GET",
		url: "pages/content_slider.php",
		data: "q="+(this.rel),
		success: function(response){
			 $("#slide_hidden").html(response);
		},
		complete: function(){
                         $("#slide_hidden").animate({'width':larghezza+'px'},1000);
		}
	});       
})