Thanks to CE's use of the Desert plugins, Model overriding is as simple as overriding controllers or views. For example, to override the 'login' method of CE's User model, you'd just create a user.rb in your own app/models directory with the same class declaration ("User << ActiveRecord::Base") and then override just the method you want to change. So:

class User << ActiveRecord::Base

  def login
     "My name is Bruno"
  end

end