A bit late response, but it is possible to do so for both Special Editions of the Monkey Island games (Secret of Monkey Island and LeChuck's Revenge).
If you are interested in translating the game, rather than editing the text to something else in one of the already supported languages, then the translation process could be trickier than just editing and re-importing the text. It actually depends on the charset of the target language and you will probably need to edit the font files too if the target language uses non-latin characters outside those already supported by the game.
There is a related discussion topic about it over on lucasforums.com
I also created a tool in python for the purposes of the (fan) greek translation for the games. It is currently on git hub as an open source project. Note that the binary version linked in the aforementioned lucasforum topic is old (superseded), so I suggest that you use the source code instead.