Just wanted to let you know that I've posted a new cookbook where I explain how to localise a Creative Suite extension. You can find it under http://cookbooks.adobe.com/post_Localizing_a_Creative_Suite_5_extension-17410.html.
I've also posted a sample to go with it that you can download from Extension Builder by selecting:
File > Import > Other > Adobe Creative Suite Extension Builder > Remote Creative Suite SDK Samples > Localised
Note that you will need the latest version of Extension Builder 1.0.1 for the sample to compile properly.