The steps to get this WindowsPhone UI working are:

1. Add a reference to your Core PCL project
2. Change App.Xaml.cs so that it creates a 'new Setup(RootFrame)' during its constructor 

    var setup = new Setup(RootFrame);
    setup.Initialize();

3. Change App.Xaml.cs so that it intercepts the first navigation:

        private void Application_Launching(object sender, LaunchingEventArgs e)
        {
            RootFrame.Navigating += RootFrameOnNavigating;
        }

        private void RootFrameOnNavigating(object sender, NavigatingCancelEventArgs args)
        {
            args.Cancel = true;
            RootFrame.Navigating -= RootFrameOnNavigating;
            RootFrame.Dispatcher.BeginInvoke(() => { Cirrious.CrossCore.Mvx.Resolve<Cirrious.MvvmCross.ViewModels.IMvxAppStart>().Start(); });
        }