Short version of cross-compile script without error checking:

#!/bin/bash
export RFS=/local/my_root_file_system
make distclean
rm -rf python_for_build Parser/pgen_for_build
git checkout -- Makefile.pre.in Modules/Setup.dist configure setup.py
./configure
make python Parser/pgen
mv python python_for_build
mv Parser/pgen Parser/pgen_for_build
patch -p3 < Python-2.7.5-xcompile.patch
export PATH="/opt/my_cross_compile_toolchain/gcc-4.3.74-eglibc-2.8.74-dp-2/powerpc-none-linux-gnuspe/bin:${PATH}"
make distclean
./configure --host=powerpc-none-linux-gnuspe --build=i586-linux-gnu --prefix=/  \
    --disable-ipv6 ac_cv_file__dev_ptmx=no ac_cv_file__dev_ptc=no ac_cv_have_long_long_format=yes
make --jobs=4
sudo make install DESTDIR=${RFS} PATH="${PATH}"