Well, you need a C compiler with cross-compiling ability, so doing this reliably platform-independently is not that easy. But you can add something like this to your `config/nim.cfg`: @if i386: cpu = i386 passC = "-m32" passL = "-m32" @end
Then you can compile with `nim -d:i386 foo` or `nim -d:i386 -d:release foo`.