Use https://github.com/saghul/pythonz to install different versions of python
To install virtualenv, virtualenvwrapper et all natively (i.e, on the python "system" path of the machine), do a :
curl -s https://raw.github.com/brainsik/virtualenv-burrito/master/virtualenv-burrito.sh | $SHELL
mkvirtualenv -p ~/.pythonz/pythons/CPython-2.7.5/bin/python ~/VEnvs/MyProject
mkvirtualenv -p ~/.pythonz/pythons/CPython-2.7.5/bin/python -a ~/Rovi -r ./requirements.txt rovi