Update:
I just realized that I misunderstood your question, because you are looking for methods defined through Flex ExternalInterface class, and not those ones Shockwave ActiveX controlyourself; I am going to leave my initial answer below, as it may be useful regarding use SWFthrough C # in general.
ExternalInterface , Fun with # Flash Player 8 API , API # . ( Flash 8 Python #.)
, , , XML CallFunction() , Georges ( , , , ;)
!
SWF .NET COM-:
SWF Windows Adobe Flash Player ActiveX control, , .NET COM-.
() / Adobes, . Macromedia Flash Player # ( ), . .
, , . Macromedia Flash Player # Windows - , , / ActiveX Macromedia Flash Player, Visual Studio.NET.
, , Shockwave ActiveX control , ( ShockwaveFlashObjects Visual Studio 2008), Visual Studio, assembly Interop.ShockwaveFlashObjects; namespace ShockwaveFlashObjects, , , interface IShockwaveFlash, ( ) , #.