Mono and missing types using external library

Hi,

we're trying to make use of EmguCV, which is a pure .Net library that interfaces to the native library OpenCV. We're using Unity 3.0 beta 4 for the modern Mono version.

However, when trying to create cameras for capture, we run into some missing type problems:

Unhandled Exception: System.TypeLoadException: Could not load type 
  'System.ServiceModel.ServiceBehaviorAttribute' from assembly 'Emgu.CV'.

So I locate this type in the Mono System.ServiceModel.dll, and paste the dll into our plugins directory. Then I get this:

Unhandled Exception: System.MissingMethodException: Method not found:
  'System.Security.SecurityCriticalAttribute..ctor'.

And I find this type inside mscorlib.dll, which is also in Mono. I paste this library into the Plugins directory aswell. This causes the Unity compiler to hang for a LOOOONG time, and in the end it doesn't seem to find the type anyway - still the same error message.

Any pointers and tips on how to make this work? Is it at all possible? Any idea why SecurityCriticalAttribute is missing from Unity's Mono version?

Is there a better way to resolve these issues than just pasting various DLLs into your Plugins dir to see if it works?