Flash :: Dictionary In Sync With A Local Shared Object?

In one of the classes in my Flex application I have a dictionary, which is periodically updated from other parts of the application. It contains some sort of user preferences and I want to keep it in sync with a local shared object - the dictionary needs to be read during the class initialization and saved to the local storage when an element is changed, added or deleted.

The "Dictionary" object inherits only "Object" and does not have a change event - like the "collectionChange" in ArrayCollection. So I can't sync the dictionary just by listening for an event and manipulating the shared object in the event handler. The other possible solution would be to make the dictionary private and manipulate it using special methods in my class. Something like:

public function setValue(key:String, value:String):void
public function getValue(key:String):String
public function delValue(key:String):void

But using bindings will become a real nightmare and I will have to make changes in many other parts of the application.