embedding mono with C# "out parameters"

I'm trying to embed a C# class in a C application using libmono, but the documentation is a bit lacking.

I'm trying to call a method with the prototype void MessageToSend(out MessageObject message);

How do i represent the "out parameter"? is it a pointer-to-a-pointer to a MonoObject? Thanks.

PS. as far as libmono is concerned, are 'out' and 'ref' parameters the same?