Ok, I took a 2GB SD card and formatted it FAT32.
I put the Bathaxx exploit private folder on it, and the Hackmii installer boot.elf on the root.
I loaded Wii mode, copied the save file for the Euro version to the Wii (I'm in UK) and booted Batman, following instructions for exploit, and Hackmii installer loaded.
It said press 1 to continue then installed HBC.
Back at Wii Menu, HBC was now a channel. I loaded it and it worked fine (albeit in 4:3 aspect ratio). I took out SD card and put Nintendont
on there. I put the SD card back in, loaded up HBC, then loaded Nintendont
, just to check it was working, and it loaded fine.
Before I went down the path of installing USB loaders or adding games, etc, I decided to see if HBC could be made widescreen/16:9 on Wii U. I found a link to a 16:9 version (with various colours) and picked the dark one.
I added MMM to my SD card and used that to install the dark HBC.
Back at Wii Menu I now had 2 HBC channels, blue and black. Since the blue one was the original 4:3 one, I went into Wii settings > Data Management > Channels and deleted it.
I then went to launch the black one, but it just loops back to the Wii Menu.
I then realised it must still rely on the original HBC, so I tried to reinstall it by putting the Hackmii boot.elf back on the root of my SD, and doing the Bathaxx exploit again.
However this time when Hackmii installer loaded, after pressing 1 to continue, it said there were no known IOS vulnerabilities and it couldn't continue.