Hi guys, this is my first topic in this forum and I really need help

I love the Final Fantasy series (huahuau, well, I think if I didn't, I wouldn't be here...) but the versions out of Japan has terrible dubbing (why Tidus sounds like a Backstreet Boy???), I just can't stand this dubbing, but unfortunately I can't read japanese, so this is what I'm trying to do:
Demux the FFX: International and FFX Jap. From the Japanese version I get all the voice sounds files and transfer them to the FFX: International,muxing it in a new DVD,so, this way I can have the Japanese audio and the English menus.
Can anyone help doing this? 'Cause I have no clue about how to do this =\

Thanx