get your custpack, find the Customize.xml file and open it using notepad look for
<allowed-language>en</allowed-language>
<allowed-language>fr</allowed-language>
<allowed-language>de</allowed-language>
<allowed-language>tr</allowed-language>
<allowed-language>st</allowed-language>
<allowed-language>zu</allowed-language>

en= engish
fr= france etc.

you can add and remove languages as you like.