I'm assuming that you imported the game and you have modded your system or use another method. I don't think it is possible to change the dialog for an imported game. Since it was made in Japan, it was only meant to be played by the people in Japan. The only way to play it in English is to wait for the game to come out to America (or wherever you live).

You should check out GameFAQS and check out some of the Faqs there. It's possible they will have a translated script but I'm pretty sure that most of the Faqs there will at least tell you how to play the game and how to advance in the game. GameFAQS