How do I make a cakePHP user management and login module with roles in a separate table

How do I make a cakePHP user management and login module with roles in a
separate table

The problem I have is this: I have in my requirements a Users table and a
Roles table separated.
users(id, login, password, id_role, name, last name, telephone, ...)
roles(id, role, description)
I already have read and followed the authentication example here but it
has the role in the same table as the user's data. I don't know how can I
relate both tables in cakePHP, especially in a login module. Can someone
please help me?