i wanna speedrun this but dont have a xbox or ps4, could i use an emulator?

Yes, you can still run on emulator, but your runs will be rejected if you submit them. Because of emulator inconsistencies and how easy it would be to mod the game, emulators are banned. It's still possible to mod the game on ps3 and xbox360, but it's a much longer process to do that and most people don't understand how it works. The few that do are modding multiplayer and have no interest in speedrunning.

Basically, if you want to run the game on emu, we won't stop you. But your runs aren't allowed on the boards.