it's not really easy thing to undub things in PS3. Like in Shiroishiki Monogatari and White Knight Chronicles, you cant just swap audio files by unpacking the psarcs with and repacking the psarcs with japanese audio.
Hacking on EBOOT is required, it might be minor changes but mostly you need to repad almost all audio files to make the undub work.
Why not ? Please explain. I started with hacking PS2 games and have ripped down a few of them. I also haved to edit some eboot's but that was in case of dumming and linking files and so on. In the last SDK they was all Tools. Also $ony's muxing and demuxing tools.