[squid-users] how to force user to change their passwords

Hi Guys

Does anyone know how to force users to change their passwords from , let
me say, 30 to 30 days, without using pam_auth ?
And before that limit day he receives an alert telling him that his
password is going to be expired?? ( preferencially via web browser or
inside the authenticated method used).

thanks in advanced

-- 
Paulo Ricardo Bruck - consultor