I have a problem of upgrading python from 2.4 to 2.6:
I have CentOS 5 (Full). It has python 2.4 living in /usr/lib/python2.4/ . Additional modules are living in /usr/lib/python2.4/site-packages/ . I've built python 2.6 from sources at /usr/local/lib/python2.6/  . I've set default python to python2.6 . Now old modules for 2.4 are out of pythonpath and are "lost". In particular, yum is broken ("no module named yum").
So what is the right way to migrate/install modules to python2.6?
There are a couple of options...

If the modules will run under Python 2.6, you can simply create symbolic links to them from the 2.6 site-packages directory to the 2.4 site-packages directory.
If they will not run under 2.6, then you may need to re-compile them against 2.6, or install up-to-date versions of them.  Just make sure you are using 2.6 when calling "python setup.py"

...
You may want to post this on serverfault.com, if you run into additional challenges.
Transition from Python2.4 to Python2.6 on CentOS, module migration problem