For the portrait-secondary, landscape-secondary states, we could hack System App with changing the value of `screen.width` as `window.innerWidth` in https://github.com/mozilla-b2g/gaia/blob/master/apps/system/js/orientation_manager.js#L31. After that, System App will think we are the real device.

Then we could also change the `screen.mozOrientation` as the state we want with the below script.
```
var screen = {
  mozOrientation: 'portrait-secondary'
};
```
And System App will change the orientation we want, like http://jsfiddle.net/Nj83s/.