wget http://www.python.org/ftp/python/2.5.2/Python-2.5.2.tgz
tar fxz Python-2.5.2.tgz
cd Python-2.5.2
./configure
make
sudo make altinstall

ln -s /usr/local/bin/python2.5 /usr/bin/python2.5

wget http://www.python.org/ftp/python/3.0/Python-3.0.tgz
tar fxz Python-3.0.tgz
cd Python-3.0
./configure
make
make altinstall

ln -s /usr/local/bin/python3.0 /usr/bin/python3.0