You have to run the development version of Ubiquity to test out the new feature - alternatively you can wait till next beta is released and run that instead. I am hopeful this will happen within a week, but I can make no promises.
Satyr also created this example to test the feature, so if you are having problems, perhaps this can serve as a guide (indeed the rest of the page might also help)
https://wiki.mozilla.org/Labs/Ubiquity/Writing_A_Search_Command#Searching_with_a_different_charset
It is easiest for you if you use the editor in "Hack Ubiquity", but as I said, you will need the latest development version to use this feature.
Best regards
-- cers / Christian Sonne