To install:

python setup.py build
sudo python setup.py install

To run:

megahal -h

As a lib:

from megahal import *
megahal = MegaHAL()
megahal.train('/path/to/some/file')
megahal.learn('some phrase')
print megahal.get_reply('hey, wazzap')
megahal.sync()  # flush any changes to disc
megahal.close()  # flush changes and close