Ok, I don't mean to be short but I'm about to lose my mind and I've been doing this all day. I cannot get USB Loader GX to recognize my backup, it won't show up in the menu at all. I tried WiiFlow but it rejected my cIOS saying it needed 249 rev 6 - I only know how to install 249 from the cIOS installer and I'm pretty sure I have the latest version, and finally, I got the farthest with NeoGamma, managing to load the game's channel music but no picture, but it broke the loading operation and gave me an error message.
I've used the backup manager to turn the ISO file into a WBFS file, I've done this several times and I know the actual ISO works because the disk works and the ISO works in Dolphin. I followed this guide:
http://lifehacker.com/5518518/how-to-back-up-and-play-your-wii-games-from-an-external-hard-drive but tried to download up-to-date files since the ones it links to are out of date, and I also googled around to see if anyone else was having my problems with the backup manager.
As a side-complaint, I really wish modding a Wii was as easy as modding a PSP. -_-