You should get the source code from its most current Subversion version at http://codespeak.net/svn/psyco/dist/. The command is:
svn co http://codespeak.net/svn/psyco/dist/ psyco-dist
People unfamiliar with Subversion or whose Subversion access is firewalled can use a web grabber (e.g. ``wget -r http://codespeak.net/svn/psyco/dist/ -I /svn/psyco/dist``), or download a snapshop at http://wyvern.cs.uni-duesseldorf.de/psyco/psyco-snapshot.tar.gz.
Note that the Subversion tree is considered the latest official release. It evolves slowly and it is more stable than the packaged version. But if you really really prefer official releases (though there is not much point, Psyco being stable and slow-changing nowadays), have a look at http://sourceforge.net/project/showfiles.php?group_id=41036.
To install from the source, run the top-level installation script setup.py:
python setup.py install
Warning, many Linux distributions (e.g. Debian) ship with an incomplete Python. You need to install the ``python-dev'' package for this to work.
As usual, other commands are available, e.g.
python setup.py build_ext -i
will compile the C source and put the result directly into the py-support/ subdirectory (no administrator priviledge is required). After this step, the py-support/ directory is a complete package (exactly as found in the binary distributions) that you can rename to psyco and copy around.