Using GCC on Mac OS to Compile C Program for MS-DOS (DOSBox)

I am running GCC 4.2.1 under Snow Leopard on Mac OS X. I want to use it to compile some old C/C++ DOS games I wrote 15 years ago so that I can run them under DosBox. To do this they obviously need to be compiled in DOS executable format, can anyone tell me how to do this using GCC please?

Thanks!