Cripes, stop bumping this thread. Also if you want a thread moved use the report button and say you want the thread moved or you can PM a mod.
Also if the Japanese ROM and American ROM are very similar, it should be easy to find differences that you can copy over via a hexeditor.
Alright, I'm sorry I keep bumping this thread. I'm just having no luck on anybody helping me on this problem and it's frustrating me. I think putting this in the Newcomer's Board was a bad idea, I should have put this in the ROM Hacking Discussion section.
I might move this thread to that section. I'll probably have better luck on there, if not, I'll just give up on this hack and move on.
I tried finding the hex values using a hex editor a long time ago, but I had no luck finding them because I don't know which values to look for in the roms.
If somebody knew the answer, he would have posted it. So it surely requires some work. I may be able to help but have currently not the time, sorry.
If the compression scheme is standard (Nemesis for example), I think there's an utility that can look into the ROM to check where potential nemesis-compressed graphics are.
The problem will be that your new gfx won't surely be the same size than the old, and if they are bigger, you'll have to move them at end of the ROM to prevent erasing data. It isn't easy stuff if you don't know asm.
If you can help me, that would be great. But take your time, I'm not in a hurry.