Create a folder in cache0 called VitaShell (cache0:VitaShell).

An english translation is included in the release (english_us_translation.txt).
You can translate it to your language and then put it at cache0:VitaShell/x_translation.txt, where 'x' is a prefix from this list:

japanese
english_us
french
spanish
german
italian
dutch
portuguese
russian
korean
chinese_t
chinese_s
finnish
swedish
danish
norwegian
polish
portuguese_br
english_gb

For the moment the language text file MUST be encoded in ANSI. This will be improved in further releases.