If your OS does not provide virtualenv it can be very easily installed as described following this link.
If you do not wish to use a Virtual Environment to install GeGeDe and its dependencies you can instead install it into your “user area” by passing the ”--user” option to python setup.py.
GeGeDe relies on the lxml module to export GDML and any other XML based formats. Many systems will supply this as an OS-level package (python-lxml on Debian). If your OS can not provide it the GeGeDe installation procedure will attempt to download, build and install it. This requires the development versions of the libxml2 and libxslt to be available. If your OS does not provide these they will not be installed automatically. It will be your responsibility to provide them. On Debian they are provided by the libxml2-dev and libxslt-dev packages.