I use Moq for my unit tests. To test internal interfaces I have to declare the InternalsVisibleTo attribute to the DynamicProxyGenAssembly2 assembly.
We run our tests ob
DynamicProxyGenAssembly2 is a temporary assembly built by mocking systems that use CastleProxy like Moq or NSubsitute. It is generated when the mock is needed and disposed of after the tests are finished.
As for the Expose Internals method than there is a RhinoMocks solution that would work for your Moq one with minimal changes:
http://ayende.com/Wiki/Rhino+Mocks+-+Internal+Methods.ashx?AspxAutoDetectCookieSupport=1