How to add/change a class to the buttons tooltip and in a link

How to add/change a class to the buttons tooltip and in a link

I want to change the existing class for the button and tooltip in the following link.  How can I do that?

  1. $("<a>")
  2.               .attr("tabIndex", -1)
  3.               .attr("title", "Show All Items")
  4.               .tooltip(   //change class here)
  5.               .appendTo(this.wrapper)
  6.               .button({
  7.                         //change class here
  8.               })
  9.               .removeClass("ui-corner-all")
  10.               .addClass("custom-combobox-toggle")
  11.               .mousedown(function () {
  12.                   wasOpen = input.autocomplete("widget").is(":visible");
  13.               })


    Class for button icon 
    1. .ButtonStyle { background-image: url('../Arrow_Down.gif'); margin: 0; border: outset; height: 22px; width: 20px; padding: 0; }