When I run the commmand
pip install virtualenv
I get:
Installing virtualenv script to /usr/local/share/python
If you want to manually decide where you want packages to reside, you could always download the source distribution to a directory of your choice with the following:
pip install -d
But when you install, I think you probably want to put the executable console scripts (as defined in the package's setup.py file; like virtualenv for example) in a directory included in your $PATH environmental variable.
You can specify this manually by doing the following:
sudo python setup.py install --install-scripts /usr/bin/
orsudo python setup.py install --install-scripts /usr/local/bin/
Let me know if you have any other questions...