[drupal-support] Help to create a "special" user

[Abalieno]

I need to create a special role/user on my site.

Basically I want the users to log in with an username and password I provide 
without registering new accounts. It should work as a just multi-user role 
with specific permissions.

The problem is that anyone can log-in and modify the password. So, how can I 
lock the access to the user page even for the same user?

I'm looking for a small mod in order to add this option in the access 
control page. So I can lock the account properly.

-HRose / Abalieno