Usage of twsh is quite simple. Just copy twshrc to ~/.twshrc and enter your twitter login credentials. I know this is not the most secure manner of doing this, but I will eventually implement something better.
The library from http://code.google.com/p/python-twitter/ is necessary as well as its dependencies.
Until now only very basic commands are implemented:
refresh: Get newest tweets from friends
public: Get tweets from yourself or a provided user
tweet: Post an update
friends: Get friends list
quit,logout,exit: End twsh
More secure storage of user credentials
Offline storage of tweets to only fetch newest ones
Better exception handling