You cannot use the C# assemblies with Xamarin or MonoMac, however you can use the source code of the client libraries and "hack" them for use with those. I have done it for Xamarin MonoTouch earlier, but have not updated them with newer library versions, so it is definitely possible.
Basically, from what I remember, I had to comment out methods that dealt with things only available on Windows or in .NET, like Bitmap, named pipes, etc. Some methods I had to change the code in in order to handle things in MonoTouch, such as NSDate, etc.
It was doable, took me a few hours one night. Unfortunately the classes now contain lots of proprietary code that I've added since then so I am not in a position to share the files as they are, but I'd be happy to help you get a Xamarin version going.