How to modify the template path for ActionMailer used in a Ruby script ?

I am testing a ruby 1.9.2 script (it'll be run in a cron task
later...) in which I am trying to use ActionMailer
All my files are in a single folder 'joinus_email

- joinus_email
    joinus_email.rb
    notifier.rb
    - notifications
        joinus_email.html.erb
        joinus_email.text.erb

running the script joinus_email.rb, (in which I defined the
ActionMailer::Base.smtp_settings)
mail = Notifier.joinus_email("john.doe@acme.com").deliver

is raising an exception :
exception: Missing template notifier/joinus_email with
{:handlers=>[:erb, :rjs, :builder, :rhtml, :rxml], :formats=>[:html], :locale=>[:en]}
in view paths

notifier.rb
class Notifier < ActionMailer::Base
  default :from => "system@example.com"
    def joinus_email(destination, coupon)
      @url = "http://example.com"
      mail(:template_path => 'notifications', :to =>
destination, :subject => "Welcome") do |format|
        format.html
        format.text
      end
    end
end

I believe there is something wrong with the :template_path =>
'notifications' parameter...
I tried a relative path : " ./notifications" same error raised
I also tried to define upon initialization : TEMPLATE_ROOT = "./
notifications" in the joinus_email.rb script , same error raised ...

any suggestions ?

[SOLVED] using ActionMailer::Base.prepend_view_path('./') and
changing the notifications folder name to notifier