At the moment NCrunch doesn't officially support Metro style applications. For metro apps to work correctly with NCrunch, they need to be carefully sandboxed in a manner that is consistent with how they would work in a runtime environment ... and with the framework still being so new, there is very limited documentation on how to effectively do this. I hope to add support for metro as part of a longer term goal.
The upcoming 1.41b release (due out very soon) will introduce the ability to find and execute the Metro tests, though the tests will not yet be sandboxed in a metro environment and thus many of the WinRT calls will fail.
Cheers,
Remco