Getting the ri18n to dynamically switch locales without rest

I have a situation where i got my app working with ri18n using these
instructions http://thread.gmane.org/gmane.comp.lang.ruby.rails/16703
.I
want to find out how to get the app to switch languages dynamically,
For one language at a time it works perfectly without any errors or
bugs.
This is particularly because i am new to ruby and rails.