How to use HTML5shiv with ajax calls data results

Question

i'm making an ajax call like this:

$.ajax({
          type: "POST",
      url: action,
      cache:false,
      success: function(data){

                  alert($(data).find("*").html());

    }

});

all browsers (exept IE 8 and 7) displays correctly the alert i put inside the SUCCESS. in IE i get an "undefined" message.

data contains some HTML5 tags and i know that is for that reason why it doesn't work.

I've already put HTML5shiv in my header but it works for the normal pages and not for ajax calls.

How can i call HTML5shiv on my "data" results?

i've already tried with innerShiv as well, but the author says that it is not reccomended anymore because html5shiv now patches for the innerHTML issue (http://jdbartlett.com/innershiv/)

many thanks, i'm going crazy with this issue...