I add the "plain text password" field as the documentation stated. However it appears that only new passwords are being added to it. How can all previous passwords be added to that field?
It can't do that as the passwords are not anywhere to populate the information. The next time a user logs in it updates (as the plain text password is available). Although having a users password available is neat sometimes you __really__ do not want to store them! Most times there is a way around the perceived need, why do you need it? Might be able to suggest an alternate solution.