Pyllar can be downloaded from the downloads section of its sourceforge page. Download the archive and extract the source code in the site-packages directory of your Python install.
Pyllar is a Python package, so it requires Python 2.4 to run (since the Python wrappers for VTK don't yet work with 2.5). It also requires the following packages:
On Linux, these packages can be installed with your favorite package management system. On Windows, these packages are all included in the Enthought Python Distribution.