The code in your above post was an experiment. I kinda hit a wall on it, and need to think about it a lot more :(
As IronScheme currently uses an incremental compiler approach, all code is compiled to memory, with the exception of the bootfile.
I hope to someday make it fully compiled (I have experimented with some ideas).
For now the best way to call Scheme from C# is to the approaches shown in the documentation.
If you are using .NET 4, you can try using (and improving) the 'dynamic' proof of concept I did.
I also hope to improve on this once .NET 4 goes RTM.