python project-specific modules installation approach
Technically for any Python module to be "installed" you just have to add it to the sys.path variable, so that Python can find and import it. 
Same goes with django apps, which are Python modules. As long as Python can find and import the django application, you just have to add it to INSTALLED_APPS in settings (and maybe few more steps usually described in the application, e.g. adding urls etc).
I'm experienced in PHP and recently started studying Python, and right now I'm on creating a small web project using django. And I have a conceptual question about approach to installing modules in Python and django. 
Example: based on expected needs for my project I've googled and downloaded django_openid module. And obviously I want to install it to my project. 
However, when I do it the prescribed way (python setup.py install) it installs it to python dir as a python module. Thus this module becomes not project specific, but system-wide. 
So, what is generally right approach to install project-specific modules in python? 
Based on my PHP experience it looks strange to install high level functional modules into the python itself. I'd rather expect it to be installed in the project library and included in the project on runtime. 
Or do I loose something important here?
I've googled around, but as long as this is rather a conceptual approach question - keywords search doesnt work good in this case.