Easiest option would be to leave it at 4.2E. Objective 1 of the Modify ANY Wii 4.3 & below, Up to 4.3, any serial, all wii colors, any region thread shows that the latest "homebrew friendly" firmware is System Menu 4.2.
The ModMii for Windows, Mod ANY Wii w/ Ease (no wi-fi required) thread may...