I18n in ruby scripts

Hello, I created a ruby script for my RubyOnRails application that
send a mail to my application users. This script is executed using a
cron job everyday at midnight. Ok so that part works just great. My
problem is that I have to use RubyOnRails I18n system to translate a
large part of the emails sent and it doesn't seems to work
(translation is not done). I'm using the RubyOnRails built in I18n
system (no plugin or anything else).
Anyone have a solution?

Thanks for the help,
Olivier Rouhaud.