Nordic Serial Interface Board C Compiler and Dev Environment

I need to modify the code in the Nordic Serial Interface Board. Can anyone tell me which C compiler and development environment was used? I am a PIC guy and totally inexperienced with AVR. I have installed AVR Studio 4 and WinAVR and created a project but get a ton of errors when I try to compile. Any help would be appreciated.

I think that they use the IAR compiler.

Leon