How to Pass User Defined Class objects from C++ to C# using CLI

Hi,
 
I am a C,C++ programmer and new to C#. We a C# application which needs to be integrated with an C++ dll. I am using CLI to accomplish the same. There are a lot of C++ APIs that need to be called from C# application, additonally, each of these API contain a lot of user defined class objects as arguments. My question is how to handle passing of C++ class objects to C# using CLI? Secondly, Is there any similiar solution like "IKVM" (C#<->Java) for C#<->C++?
 
Thank You for Your Help,
Deepak