I use Plone 4.3.9, and I'm doing a intranet, all users come from Samba4.
But, I created a new dexterity content types (with this fields Name, Photo, and birthday [Day and Year]) and in index page to show up and I handler users and birthday to appear in index
I want put in garbage the way that I do (described up), and to expand my knowledge in Plone, I want override users Plone or do something like to put one or two more fields to set month and year of birthday in default users plone.
On Plone 4 and 5 Plone data is controlled by plone.app.users.
On Plone 4 you must rely on this tutorial: https://pypi.python.org/pypi/collective.examples.userdata/2.1