Can Ember on and observer be chained and applied to one method using the new Ember.computed syntax?

I have recently started switching from syntax like this:

Ember.Object.extend({
  someMethod: function(){
    // do something
  }.on('init')
});

to this:

Ember.Object.extend({
  someMethod: Ember.on('init', function() {
    // do something
  })
});

Because it seems to be the convention nowadays and I hear it works better in add-ons.

However, occasionally I want to chain behaviors of the method like this:

Ember.Object.extend({
  someMethod: function(){
    // do something
  }.on('init').observes('someProperty')
});

Is there a way to achieve this with the syntax that doesn't count on having function prototypes modified to include on and observes methods?