5 easy steps:
1. Open ISO with WiiScrubber and extract main.dol
2. Open main.dol with Generic Wii Patcher
3. Change the video mode with PAL-2-NTSC button
4. Save main.dol (you can close Generic Wii Patcher)
5. Replace saved main.dol in ISO with WiiScrubber (now, you can close WiiScrubber)