rails 3 + devise: how to modify the mailer method for confirmation emails to add user's second email address

Background: In our app, we often have a sales rep do the setup for our customer using the salesperson's computer (often customers don't have access to their email at the time we set them up). So we're thinking to add a field to the devise registration form for the sales rep's email address and have the confirm link ALSO go to that email address.

Question: Is there a way to tell devise to bcc (or cc) the initial confirmation email (only the initial confirmation email) to an (optional) "backup_email" email address that is also provided on the new user registration form?

Alternatively, is there a way to 'disable' the confirmation email process but ONLY when a certain code is entered into the registration field?

I know how to add another field to the devise registration form, but I don't see how/where to modify the devise mailer code so when a confirmation email is sent to the "email" address it ALSO goes to the "backup_email" address (if any, sometimes it's blank).

Thanks to Johnny Grass!

I did rails generate mailer CustomerUserMailer and added

#config/initializers/devise.rb
config.mailer = "CustomUserMailer"

my custom mailer looks like:

# app/mailers/customer_user_mailer.rb
class CustomUserMailer < Devise::Mailer
  def headers_for(action)
    headers = {
      :subject       => translate(devise_mapping, action),
      :from          => mailer_sender(devise_mapping),
      :to            => resource.email,
      :cc            => resource.backup_user_email(action),
      :template_path => template_paths
    }
  end
end

Then I moved the 3 mailer templates FROM views/devise/mailer to views/customer_user_mailer (otherwise the emails are empty)

Then I added a method to my User model called backup_user_email() that retu