Hi, if you use the new Website interface that is bundeled with eZ Publish 3.9 it uses it's own translation files, so it is only a few strings needed.
EDIT: A few strings is a underestimate, but it's a lot less then the translation file in eZ Publish itself.
EDIT2: You can also translate only the strings you want to, look at some of the translations in the link below. This goes for both eZ Publish and the website interface.
The translation files can be found in svn: http://svn.ez.no/listing.php?repname=extensions&path=%2Fezwebin%2Fstable%2F1.1%2Fextension%2Fezwebin%2Ftranslations%2F&rev=0&sc=0
And if you upload the translation to our issue system (Bug reports) as an enhancement to the website interface, we could add it to next version.
