pychats can be installed using pip:
$ pip3 install pychats
pychats is written for Python 3, and does not support Python 2.
If you get permission errors, try using
$ sudo pip3 install pychats
The repository for pychats, containing the most recent iteration, can be found here. To clone the pychats repository directly from there, use:
$ git clone git://github.com/samirelanduk/pychats.git