handling models with embedded objects in the payloads with ember data

I'm trying to determine how best to define my models. I'm trying to represent an asset. Ex: car, tv, house, etc.

Here's the payload coming from my server:

{
    "asset": {
        "id": "1b0b77a2-28d7-488e-9a6f-8a202c297593",
        "created_at": "2015-03-19T09:16:43+0500",
        "updated_at": "2015-03-19T09:16:43+0500",
        "name": "Flat Screen Tv",
        "properties": [
            {
                "name": "brand",
                "value": "Sony",
                "public": false,
                "family": false,
                "friends": false
            },
            {
                "name": "price",
                "value": 1000,
                "public": false,
                "family": false,
                "friends": false
            }
        ]
    }
}

It needs to get POSTed back in the same format. How can I define this model with ember data? The properties are hanging me up. I thought I could just define a transformer but then noticed that changing values in the transformed data doesn't update the asset's "dirty" flag. I need that dirty flag to be updated when the properties get changed. Any ideas?

// app/transforms/array.js
import Ember from 'ember';
import DS from 'ember-data';

export default DS.Transform.extend({
  serialize: function(value) {
    return value.toArray();
  },
  deserialize: function(value) {
    return Ember.A(value);
  }
});

Here's my asset model definition.

import DS from 'ember-data';

// app/models/asset.js
import DS from 'ember-data';

export default DS.Model.extend({
  name: DS.attr('string'),
  createdAt: DS.attr('date'),
  updatedAt: DS.attr('date'),
  properties: DS.attr('array')
});