Editing XAML on the fly

Question

I need to Create a Metro style application without using the static XAML description for the UI. This application needs to be able to accept XAML code and render it to the screen, sort of like what is done in the Designer of Visual Studio 11 for Windows 8.

Any help? I get the feeling that there must be some built-in function that should do this in .NET, but so far I have been unable to find it. I think there already is such a function in .NET for Silverlight (XamlReader.Load()), but it does not appear to be working in .NET for Metro Applications.

Thanks.