Hybrid 16bit/32bit exe

[Stanimir Vlad]

I wanted to know how to create using c++ a program that will run both 
under dos (16bit) and windows (32bit).So that when i execute the exe 
under windows it will skip the dos part and use only the windows part.
I was told that Visual C++'s linker allows you to pass it as a parameter 
an MS-DOS stub program that you want to use when your program is 
executed in DOS.
http://msdn.microsoft.com/en-us/library/7z0585h5(VS.71).aspx
I want to know how i can do this using gcc and how i can croscompile a 
dos exe under windows.