Create a directory next to "./update.sh" to follow a twitter user. For example if you want to follow @notch, create a directory named "notch", if you want to follow @KarenGillan2, create a directory named "KarenGillan2".
Then run ./update.sh
Then run ./aggregate.sh
Then open tweets.xml in your browser.
pyxpath is packaged with this program but if you want a clean install of it see : https://github.com/playest/pyxpath#install
In any case you will need to install html5lib, lxml and BeautifulSoup (pip install -r requirements.txt).
If you only have access to python 2.6 (yes, I'm looking at you.) you can delete rename pyxpath26.py into pyxpath.py (not working apparently :().