Please try to override the 'setText' method of textbox.
(function($){
var setText = $.fn.textbox.methods.setText;
$.fn.textbox.methods.setText = function(jq, text){
return jq.each(function(){
$(this).textbox('textbox').attr('value', text);
setText.call($.fn.textbox.methods, $(this), text);
})
}
})(jQuery);