Add ‘Right Now’ widget to custom dashboard

Question

I’ve got to know it in Make WordPress UI. The plugin Dashboard uses a very interesting technique:

add_action( 'load-index.php', array( $this , 'override_dashboard' ) );

public function override_dashboard() 
{
    if( !isset( $_GET['page'] || 'custom-dash' != $_GET['page'] )
        return;

    if ( get_current_screen()->in_admin( 'site' ) ) {
        require dirname( __FILE__ ) . '/dashboard-override.php';
        exit;
    }
}

And then it proceeds to fully rebuild the Dashboard with the file dashboard-override.php, with a brand new clones of the Widgets, like rightnow.php. I think it’s worth emulating.