Thanks Phil,
Managed to get things linking by adding the:
-dylib_file' '/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib:/System/Library/Frameworks/OpenGL.framework/Versions/A/Libraries/libGL.dylib'
linking option under: Project->Compiler Options->Linking Tab as suggested.
Not quite sure why I need the path to the OpenGL libs in twice, but it didn't seem to work with it in just once. So that's my carbon applications building okay... now to try to get the things actually running!