Unfortunately this kind of programming isn't possible - the advantages of things like Ruby/LUA etc. are that they are scripting languages - they can run live.
The problem with C# in this case is that it is a compiled language - hence code cannot easily be deployed at runtime. This may seem a disadvantage but when you consider things like the strong typed integrity the model gives you it makes a lot of sense. This is why most "script" interfaces are LUA based.
C# is the only option for EGM because of the Xbox support.
One alternative is to code in the engine directly using extension classes for instance, and using the comment system as an indicator for running code. This of course means some kind of string parsing etc, but it means for easily compilable code that is extendable too - so in general anyway this method should be preferred.
We will discuss the possibility of using some new C# features i.e. Method bags to make extending the engine much more component based? What would you think about that approach?
It may not fit your needs but it may be possible to invoke methods that have been pre-coded from events, again sticking to the rules of pre-compilation, but this is simply a GUI for the former method that may even be more restricted.
Sorry if this is all too programmer oriented, but I assume if you want to code in the first place you'll know how to do all of the above.