I do not understand your question fully... If the following answer does not solve your problem try to rephrase it, or give a example command line for gcc, or add screenshots..
If you want to add defines to the compiler settings you can add them to
Project->Build options->Select the project name on the left->Compiler->#defines->add
i do not think the preprocessor understands "true" and "false".. i would use "1" and "0"