Problems with MSTest private accessor and generics

Question

I'm trying to test a private class in an assembly and so have tried to create a private accessor to the assembly. However when I compile the unit test assembly I get an error "Signature of the body and declaration in a method implementation do not match.  Type: 'Indexer'.  Assembly: 'ClassLibrary_Accessor, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'.    TestProject".

The definition of the Indexer type is

    public class Class1
    {
        private class Indexer : IComparable<Indexer>
        {
            #region IComparable<Indexer> Members

            int IComparable<Indexer>.CompareTo(Indexer other)
            {
                return 0;
            }

            #endregion
        }
    }

The problem seems to be due to the explicit implementation of the IComparable interface as if I swap to an implicit implementation the error goes away. Is this a bug in the unit test framework?

Is there a work around? The class that the error is raised for is not the one I am interested in testing, however there are a reasonable number of similarly implemented class in the assembly. Can I restrict the accessor to only wrap the class that I am interested in?

Many thanks