If you have bootmii as boot2 installed you have a lot of room to work with.
1st- Backup Your Nand
2nd- Follow the 4.2 guide linked below
3rd- Reinstall the latest firmware for the wiikey, and run the config disk.
Now 4.2 will not play out of region games using your chip
- You could try to install IOS70v54321(IOS60-patched).zip with wadmanager. See if this will fix your region issue with disks. It may.
Otherwise, use dop-ios-mod v11.5 with ios249
-remove stubed ios files
-install ios60 with patches
-then Install system menu 4.1 (after ios60)
Let me know how it goes.