Hi,
You are correct that when the password storage is set to hashed the passwords cannot be recovered to plain text.
Are you migrating away from mojoPortal or only trying to provide users a login to another system?
If you're wanting to provide your users with a login to another system you have a couple of options; 1) write a module/plugin/addon for the 'other' system to use your mojoPortal site for authentication (users) and authorization (roles); 2) setup an LDAP directory and connect both systems to it (with this option you'll need to map LDAP users to existing users in mojo and passwords are probably going to have to change because the authentication piece of the puzzle would be handled by LDAP).
Simply put, the passwords are hashed and there is no way to get them back to plain text.
HTH,
Joe D.