Access Themes/Generic.xaml via reflection

Is there any way to access the Themes/Generic ResourceDictionary using reflection?

I tried digging through Application.Resources but this appears to be the wrong place. Then I tried analysing the Assembly's ResourceStream but that wasn't succesful either.

So does anyone know how I can get the instance of the mentioned ResourceDictionary from an assembly?

Before someone asks "Why" => because i want to mess with it.

This is the closest i got, but it throws errors that some parts of it cannot be loaded, so I assume its a "copy" and not the one used?

        System.Uri resourceLocater = new System.Uri("/ASMNAME;component/themes/generic.xaml", System.UriKind.Relative);

        ResourceDictionary dictionary =(ResourceDictionary) Application.LoadComponent(resourceLocater);