Your code looks good and runs well, but I'm still a bit concerned about
performance here.  In the example test cases you have, there's not a
problem, but consider your code here:

        el['on' + type] = function(e) {
                             e = e || window.event;
                             var listeners =
arguments.callee.listeners;
                             for (var i=0, len=listeners.length; i<len;
i++) {
                               var l = listeners[i];
                               if (l) {l.wrappedFn(e);}
                             }
                           };

Here is the relevant W3C recommendation
(http://www.w3.org/TR/DOM-Level-2-Events/events.html):

quote
Any exceptions thrown inside an EventListener will not stop propagation
of the event. It will continue processing any additional EventListener
in the described manner.
/quote

I was concerned about your implementation's synchronous implementation;
however, it appears that the standard is not clear on whether multiple
events should be called synchronously or asynchronously.  (I believe
the FF is asynchronous for multiple events, which would improve
performance considerably.  Need test to determine whether this is the
case.)

However, what your implementation is missing is fallback error
handling.  If an error occurs in one handler it will prevent the rest
of the handlers from executing.

That's all.  Good work otherwise.