'Assuming the cwd is the extracted python package, execute a simple:
python setup.py install --prefix=BLA
BLA will be a temporary directory that everything installed will
be picked out of and rsynced to the appropriate place under
install_dir afterwards.
Afterwards, it deconstructs the extra lib/pythonX.Y/site-packages/
directory tree that setuptools created and moves all installed
site-packages directly up into install_dir itself.
:param install_dir the directory for the install to happen under.
:param setup_py - The name of the setup.py file to execute.
:return: True on success, False otherwise.'

def _install_using_setup_py_and_rsync(self, install_dir, setup_py='setup.py', temp_dir=None):

    if (not os.path.exists(setup_py)):
        raise Error(('%s    does    not    exist    in    %s' % (setup_py, os.getcwd())))
    if (temp_dir is None):
        temp_dir = self._get_temp_dir()
    try:
        status = system(("'%s'    %s    install    --no-compile    --prefix='%s'" % (sys.executable, setup_py, temp_dir)))
        if status:
            logging.error(('%s    install    failed.' % self.name))
            return False
        if os.path.isdir(os.path.join(temp_dir, 'lib')):
            temp_site_dir = self._site_packages_path(temp_dir)
        else:
            temp_site_dir = temp_dir
        status = system(("rsync    -r    '%s/'    '%s/'" % (temp_site_dir, install_dir)))
        if status:
            logging.error(('%s    rsync    to    install_dir    failed.' % self.name))
            return False
        return True
    finally:
        shutil.rmtree(temp_dir)
