I added support to run ctypes from a CVS sandbox without the need to
install the package. This even works for different Python versions
on the same machine.

This behaviour is triggered by the presence of a .CTYPE_DEVEL file in
the ctypes package directory.

Just do a 'setup.py build' and insert the top-level directory into
sys.path (with setting the PYTHONPATH env variable, with a .pth file,
or however), and it should work.