You could change the "say/emote/etc" text content to the Perl quests and a lot of the game would be in the wanted language. But be careful of what you change; for example "$name" is a variable that can't be changed.
Also , you might be able to "hack" into the source and change things in there (like what the vendors say, when you right-click them).
I don't think there's much you would need to change in the database that would affect the language.
Be sure to back up often before you start
