You need to do more than just change the region. You also have to change the TV video format to the corresponding type. as far as I know it only works on dvds. Blu ray region code is different from dvd region on ps3. It has a slightly more tamper resistant protection.
Does this only work with DVDs, or PS2 games, too? I have a couple of Japanese PS2 games I've been trying to get to run this way, but it's not working. I dunno what I would change the DVDTV thing to for NTSC-J, though, so maybe that's it. Using 3.55 Kmeaw CFW and Comgenie.