I am using a Jython virtualenv where I can install whatever software via pip or via easy_install, but there is a software that is not registered yet and the installation mod
Basically you need to install the installtool first. To do so see the doc linked below.
install this: http://peak.telecommunity.com/dist/ez_setup.py
(see here:http://www.jython.org/jythonbook/en/1.0/appendixA.html#setuptools)