Use cartodb.js to add a torque layer from a named map with auth_tokens enabled

gistfile1.txt

    var layerSource = {
      type: "torque",
      options: {
        auth_token: '{yourAuthToken}',
        user_name: "{yourCartoDBUsername}",
        tile_style:"{torqueCartoCSS}",
        named_map: {
          name: "{namedmap}"
        }
      }
    }

    cartodb.createLayer(map, layerSource).done(function(layer) {
      map.addLayer(layer);
    });

layer.setAuthToken() doesn't work for torque named maps, auth_token must be added to the options
The trick is that the tile_style, or CartoCSS must be defined in the layerSource definition
A viz.json for a torque layer will include the same layerSource including tile_style

Great!