Why not use the onpropertychange(msie)/oninput(firefox) event to catch content changing in autocomplete plugin, so that it can fire the search event on content changed by other event like paste from clipboard or chinese input method? Now I map the event to keydown manual outside the control :

            if ($.browser.msie) ele.onpropertychange = function() {
                $(ele).trigger("keydown");
            };
            else ele.addEventListener("input", function() {
                $(ele).trigger("keydown");
            }, false);