Yes, you can access views through their ids in another controller. The only need to assign controller object and view object to two different variables:
episode.js
var overlay = Alloy.createController("overlay");
overlay.theButton.addEventListener('click', function() {
alert('You clicked the button from overlay.xml!');
});
var overlayView = overlay.getView();
$.episodeImage.add(overlayView);
// shorter version
$.episodeImage.add( overlay.getView() );