I haven't done anything with this, but I think what you want to do is cross-compile it for DOS (or Win32, whatever the case may be). Search around for cross compiling for details. The
GCC homepage might have more information on how to do this, or maybe the gcc man pages.
Really, though, the best thing to do would be compile it under DOS, using a native compiler. Try
DJGPP, if you have access to a DOS/Windows machine.