I'm trying to create a single registration process for drupal and webmail plus

I have webmail plus up and running

I am trying to automate the registration process so each new user has their own email account
the first time they login

To do this I need access to that users password they enter at account creation and subsequently also when they change their password

I have looked into hooks but have been unable to figure out how it might be done

essentially I need to grab the users password at egistration and when submiting a password change

If someone could point me to the drupal code that handles these tasks that would help too.