README.txt
  CalendarX 0.6.6(stable)  January 03 2006
  (last modified for CalendarX 0.6.6)
by +lupa+ (lupaz on sf.net, lupa at zurven dot com)
Released under the GPL (see LICENSE.txt)

Release Summary: 0.6.6(stable) is a stable release for the i18n branch
  of CalendarX.  The release candidate has proven quite stable and very 
  few bugs have been found.  Those are now fixed, and the documentation 
  has been updated, and this should be the last release of the 0.6 branch, 
  unless new bugs are found. No new translations have been added.  
More translations!  Make calendarx-XX.po files for us!  If you can 
  translate, please do so and add your translation to the CalendarX project.  
  It's easy, follow the directions in the INSTALL.txt file in /docs.

CalendarX is a customizable, open source metacalendar application written 
for the Plone content management system on top of Zope and Python.

Read the INSTALL.txt document for details, but in essence, put the CalendarX
folder in your /Products folder, restart Zope, use the portal_quickinstaller
to add CalendarX.  Then add a CalendarX instance through Plone using the 
normal methods.  

CUSTOMIZATION:  Customize property sheets or other objects found in the 
/portal_skins/CalendarX folder.  Use ZMI to move these into your CalendarX 
instances (from the /custom folder) to restrict the customization to that 
one CalendarX instance.  This allows creation of multiple CalendarX instances
and also subcalendars (use ZMI to add new subcalendars within a main calendar
instance).

There is fairly extensive new documentation in the /docs folder, including a 
new Manual for CalendarX in PDF format.  Please read these for help in 
figuring out all the configuration.  CalendarX has lots of options, and 
reading the docs helps a lot.
 

Read more at these sites:

http://calendarx.sourceforge.net
http://sourceforge.net/projects/calendarx/
http://calendarx.org