I need to build a scripting interface for my C# program that does system level testing of embedded firmware.
My application contains libraries to fully interact with
I agree with Marc G, though it's worth mentioning that the general concept is a Domain Specific Langugage. While IronRuby/IronPython aren't strictly domain-specific, they are full-featured and it would leave you to get on with your implementation.
Visual Studio has the DSL tools, and there's the 'M' Grammar stuff you can look into.
But yeah, IronPython.