i'm not to sure since most of the people who make those hacks are not american
i have a couple of the MMZ3 mods myself and have been on their moding forum useing the googletranslator to read wut they were saying but sadly they never explained wut program they used
somehow all they need is the proper sprite sheet and animations and they can insert them in the game fully intact for the most part. i tried hacking MMZ3 with TPL but the character data is so compressed that you can't even see were the bodies are.
i really just wish i knew wut type of program they used so i could make some truly awesome CV mods with all types of characters