instead of editing the game itself (the wad?), you can try to launch the game using a game loader which has more settings, like video mode.
Wiiflow can list and launch channels installed to NAND, and you can force a video mode (which could affect the sound's speed, depending how the game is coded). try with "force NTSC 480p"
Another solution is to use EmuNAND feature.
Do use it, you need to make a copy of your console's memory to a folder on your SD or USB, and use that folder as if it was your real console. (redirected NAND access).
Wiiflow and USBLoaderGX allow you to do it, it's very easy to setup and use but it's not 100% compatible with games.
USBGX > settings > features : Dump NAND > full
USBGX > top menu > 4th icon : enable "channel on emuNAND"
Done.
You can install new games from :
USBGX > settings > features > emuNAND Wad manager
If your game doesn't work, you'll need another step, which is more complicated (called Neek), but we will see later, only if needed.
So, you have already 2 solutions:
install game to console, launch it with loader
install game to emuNAND, launch it with loader
installing to emuNAND has the advantage of free space : you can install up to 2TB of games, instead of the limited 512MB/48 games of Wii/vWii.