As long as your interfaces inherit from IUnknown you should be able to call
them from C#.  Do you have a Type Library for these interfaces?  If so you
can create an interop assembly with TLBIMP.exe or by adding a project
reference in VS.NET.  If this doesn't work or you have no TLB then you can
manually define the COM interfaces in your code.

David Stucki
Microsoft Developer Support

This posting is provided "AS IS" with no warranties, and confers no rights.

From an earlier post (April):

Use Type.GetTypeFromProgID or GetTypeFromCLSID have overloads that allow
you to specify a server name, then use this type with
Activator.CreateInstance.

Type t = Type.GetTypeFromProgID("MyLibrary.Object", "REMOTE_MACHINE_NAME");
MyLibrary.IObject obj = (MyLibrary.IObject)Activator.CreateInstance(t);

Hope this helps.

David Stucki
Microsoft Developer Support