L18n help

i need some help writing some code in rails about cookies.

what i want to do is depending on the cookie value sent i want to set
language for the page .
the code is something like
in applicationcontroller.rb

$KCODE = ‘u’ # lets go unicode, you will have less trouble …
require ‘jcode’ # and use the right string methods for utf-8

The directory where translation files (PO files) will go

I18nService.instance.po_dir = “#{RAILS_ROOT}/locale”

let’s use telugu everywhere

@lan = lan =“te”
I18nService.instance.lang = lan

what i want to do is let the user select language from drop down list
then pass that value to set the lan variable which would give the
language interface