If you already have easy_install available:

easy_install ewa

Ewa source releases are also available from the Python Cheeseshop.

To check out the latest development version:

svn co svn://svn.wnyc.org/ewa/trunk ewa

Alternatively, google code has a copy of the repository which is synced every few hours:

svn co http://eastwestaudio.googlecode.com/svn/trunk ewa