How do I specify a mapping from an Ember model to JSON?

I have an API that returns:

{id: 1, "other-property": 100}

My Ember Data object is defined:

MyApp.MyThing = DS.Model.extend({
  extId: DS.attr('number'),
  otherProperty: DS.attr('number')})

It looks like I can't use id as an attribute in an ember model, and using non-identifier field names will cause trouble. So the guide suggests I write a normalizeHash function.

App.MyThingSerializer = DS.RESTSerializer.extend({
  normalizeHash: {
    id: function(hash) {
      hash.appId = hash.id;
      delete hash.id;
      return hash;
    },
    otherProperty: function(hash) {
      hash.otherProperty = hash['other-property'];
      delete hash['otherProperty'];
      return hash;
    }
  }
});

It doesn't suggest how to re-serialize when sending back over an API. How do I do this?

Is there a declarative way to do this? It seems very cumbersome.