Hello, I've just whipped this tool up to edit Dead Rising AST files, which allows us to finally replace music in Dead Rising 1! Unfortunately, the sound effect format is not the same. I can hopefully figure out how that one works, but this'll do for now.
The tool is missing one bit of functionality, that being loop points. However, I can not see any obvious loop points, and being a raw format, i suspect it just loops right after the header. I haven't checked how well songs loop. The tool also only supports MP3 files, for various reasons.