I need this feature but I'm unsure where/how to turn it on. Could someone point me in the right direction?

Thanks,
-Tom

From "New Features in 1.2.11 lists"

Track when password was last modified

passwordTrackUpdateTime - if this is set to "on", the server will keep track of the last password update time

pwdUpdateTime - new operational attribute in entries holds the last password update time if passwordTrackUpdateTime is enabled