Authlogic - Authentication with 2 login fields

Hello

I need to authenticate a user based on two database fields living in
two different tables.

So far I have:
class UserSession < Authlogic::Session::Base

login_field :employee_code # the login
attr_accessor :employer_code # the extra login field

find_by_login_method :find_app_user

must find the employer first, and then the employee

end

However, only the employee is passed to the find_app_user method on
save.

Any tips are appreciated.

Dave