Ok, I'm feeling really dumb. I'm working with a simple color hack for Red Alloy (I swapped the green and blue channels, making him brownish instead of purplish).
I replaced the file in BrawlBox (0.62b), saved to FitZakoBoy01.pac (to test and see if an alternate color would load for the Alloys). When it didn't, I figured that it would always try to load 00.
Problem shows up when I renamed it to FitZakoBoy00.pac. It still isn't replacing the disk's file.
The file replacement code works, as it's playing Let's Brawl! in Cruel Brawl.
I have the file in RSBE\pf\fighter\zakoboy\FitZakoBoy00.pac.
BrawlBox generated a palette for the texture I'm trying to replace, and while it may not be in the same places, it should still work.
Where am I going wrong?