To my surprise and joy, I managed to build a Mac OS X hosted cross compiler targeting Windows (MingW).
I used the information found at (or through) http://www.mingw.org/mingwfaq.shtml, more specifically http://www.libsdl.org/extras/win32/cross/README.txt. With some necessary modifications, the http://www.libsdl.org/extras/win32/cross/build-cross.sh script was able to build cross binutils, as well as gcc and gpc cross compilers.
The actual build was done with gpc 20041017 and gcc-3.3.3-200402017-1 (mingw special).
I hope, I will find time (in a few weeks) to add binaries, sources and a build script for the cross compiler to my website.
The cross compiler swallows hello.pas and the resulting binary actually does say "Hello, World" at the other side of the fence. However, the question arises how reliable the cross-compiler is, as the testsuite says "if this is a cross-compiler, you can't run the test suite easily". Is it reasonable to rely on native testsuite results on both the host and the target ?
Regards,
Adriaan van Os