I don't think that's a supported scenario, for two reasons:
1- The .NET Runtime can do this for fully managed applications because it
can track dependencies and download the necessary dependant asssemblies as
needed. If you depend on unmanaged libraries (which is very likely on mixed
mode scenarios), the runtime has no way to deal with those unmanaged
dependencies.

2- The default security settings will pretty much prevent you from running
mixed mode code, because the default permissions given to code executed that
way don't allow access to unverifiable and unmanaged code, I believe. You
could try using the .NET Framework Configuration tool to adjust the security
policy to give it the necessary permissions and see if it will run that
way...