In the context map the View Class to the Mediator Class. Then anytime at view of that Class type is ADDED_TO_STAGE, the mediator class will automatically be created with it. When it is REMOVED_FROM_STAGE, the mediator will be destroyed along with it.
It is common practice to create custom Event classes for this purpose. For example, your ExampleModel could dispatch events of the type ExampleModelEvent. Your ExampleMediator should then register listeners for these events.
If you use the AS3Signals library you have two options:
Create custom Signal classes, for example ExampleModelRegisteredSignal, and then [Inject] the signals into your Mediator.
Expose your Model's signals by making them public and then [Inject] the Model into your Mediator, registering listeners for its signals.