<< cross binutilsのmake & install >>
$ bzip2 -dc binutils-20030307-1-src.tar.bz2 | tar xf -
$ cd binutils-20030307-1
$ mkdir build; cd build
$ ../configure --prefix=/usr/local/cygwin --target=i686-pc-cygwin
$ gmake
$ su
# gmake install

<< gccビルド時にcross binutilsを使うのでPATHを通しておく >>
$ PATH=/usr/local/cygwin/bin:$PATH; export PATH

<< cross gccのビルド >>
$ bzip2 -dc gcc-3.2-3-src.tar.bz2 | tar xf -
$ cd gcc-3.2-3
$ mkdir build; cd build
$ ../configure --prefix=/usr/local/cygwin --target=i686-pc-cygwin --enable-languages=c,c++ --disable-nls
$ gmake
$ su
# gmake install

<< テスト >>
$ cat > hello-win.c
#include <windows.h>
int main(void) { MessageBox(NULL, "hello, world", "hello-win", MB_OK); return 0; }
<CTRL-D>
$ i686-pc-cygwin-gcc -o hello-win.exe hello-win.c
できたhello-win.exeをWinで実行できたらOK