Martijn de Visser has created an ExternalFunction class, which allows you to generate EventDispatcher events in Flash through Javascript.
I’ve been using similar solution in the past where I had a menu in Flash and some html content changing in a different frame.
In order to track the changes in the frame with the html content I used to generate a small swf that pass Javascript variables to the main Flash menu by LocalConnection.
Martinjn’s ExternalFunction class supports a LocalConnection to receive variables and then broadcast an event.
JavaScript Events in Flash