1. cIOSCorp
2. DARKCORP
3. Priiloader/Preloader with Hacks

Any of the three should work.

 

sneek + di. its way less risky than any of the other methods
you only need bootmii installed and you can load disc and usb games from the disc channel

 

Well, older versions of cIOSCORP (v1/v2) would brick newer Wiis.

But DARKCORP is pretty safe. It's about as safe as a regular update (except official 4.2 update, which is even more dangerous than DARKCORP installation!).

That will get burned discs to load via disc channel.

And you can use various hacks with priiloader such as region free and update blocking.

...you can use priiloader with a "Force discs to use IOS249" hack without using DARKCORP, but that method has low compatibility.

So I would suggest using bootmii to make a NAND backup, then install DARKCORP.

 

[off-topic]
Even if it's as IOS, it can still dump your Wii's keys and NAND, and if something does go wrong, it can then be reflashed by an infectus NAND programmer, rather than having no backup at all.
[/off-topic]