How can we capture the user's password at signon and update PSOPRDEFN?

We currently use LDAP for authentication and have a customization at signon time that converts users to their PeopleSoft numeric User ID values (different than their LDAP user id) after they have successfully authenticated.  We'd like to be able to update their PeopleSoft profiles with their LDAP passwords.

The following suggestion was mentioned in Oracle case "E-SEC: What kind of password encryption algorithm is used with PeopleSoft 8? [ID 610737.1]"  Has anyone tried it?

"The Password in %SignonUserPswd is encrypted, not hashed.  It is encrypted with our internal, private, key.  If the user needs to have a cleartext password, they can add a variable to the signon.html page that is a copy of the password variable and then access it through the Request object."