[Distutils] Accessing config.h options ?

I'm currently trying to start looking into auto-configuration... is there a way to access the parsed config.h file from within the "config" command instance ?

Also, the config class doesn't allow defining macros (e.g. to enable full __GNU__ support in gcc). Is there a way to define per-compiler define symbols in the setup() constructor or by subclassing compiler classes ?

Thanks,