I'm not exactly sure what you want, but you may be able to find a ROM of the game on the internet, run it on an N64 emulator, and edit the memory addresses on the fly to hopefully get it to give you debug mode access. It may just be one bit, or a small string of machine code that could be edited in. Then you could just keep the modified ROM, and load it onto your N64. Like I said, I don't know what I'm talking about in this specific situation(or how it works, you may just be able to download a debug save), but good luck anyway.