Note
Only tested on Linux at the moment.
It is assumed that you already have Python installed. Installation of sgl will automatically install numpy and scipy, as they are required for sgl to work. If you want graphic support, you manually need to install vtk since it is not found via pip. Please check their website or your distributions documentation on how to install vtk.
You can install sgl system wide, just like any other python package:
$ git clone http://github.com/Kingdread/sgl
$ cd sgl/
$ sudo pip install .
# Alternative:
$ sudo python setup.py install
Note that the Python (or pip) version you use to install sgl must match the version you want to use sgl with.
sgl can be installed inside a virtualenv just like any other python package, though I suggest the use of virtualenvwrapper.
If you want to use vtk inside the virtualenv, you need to manually copy the vtk folder into your virtualenv library path. The vtk folder is usually found at /usr/lib/python2.7/site-packages/vtk, but your mileage may vary.