Anyway, to get back to the original question:
You can use any tool you feel comfortable with and you can create the necessary compiled RHP with. As I already mentioned you just need to:
- reference the right assemblies (RhinoCommon stuff, Eto stuff if you do that, System)
- type your code
- compile your code with whatever tool you have at your disposal (NAnt, CMake generated project files, devenv.exe, MSBuild, etc)
- ensure the resulting DLL is renamed with .rhp as the extension
- world domination
Really points 1 and 3 is however it is done with whatever toolset you choose. As long as you can compile your .NET code into CLR-compatilbe assembly you’re set.