Unlocking your Wii in order to be able to play games that are homebrew, imported from other geographic regions or even backed up can be a tremendous challenge, mainly because it's dangerous. How to unlock Wii (v4.2u compatible) you normally have to install a small device called a "Modchip" which can enable your Wii to run copied wii games and unlock other features for the Wii.
The bad news here is that opening up your Nintendo Wii console and messing around with its electronics will usually void your warranty.Not having any previous experience with this of modication to your Wii cn have serious repercussions.
However, there is a way around it, by installing homebrew software you don't need to install a modchip. All you need to do is get a hold of a Wii homebrew guide that shows you step by step how to install homebrew on wii. The homebrew guide or ebook shows you how to exploit some errors in the Wii prgramming that allows you to bypass the security and allow you to run homebrew on your Wii console and how to unlock wii.
Do a little bit of looking around the Internet and you'll see what I'm talking about. People all over are making these changes to their console. Just take a look in the net to see how other poeple have done it.What you need most of all is a set of instructions that walk you through the process. The best way I've found to do that is with the Wii Homebrew Installer eBook, but there are plenty of other options out there, too. These guides come with plenty of supports and helpful updates to assist you in how to unlock wii (Works with v4.2u).
To find out more about how to unlock your Wii console please feel free to visit their site. -> Wii unlock (Works with v4.2u update)