I recently borrowed a Wii from a friend, in order to do the so called softmod. I did it mainly because I wanted to play two games on this. Finally, the Softmod was too easy to make.
The main thing is that your Wii must have the firmware version 4.3 installed, so it's good time to upgrade it from the system's choice if the installed version is not the v4.3. An SD card and an adapter to connect the SD card to the PC. It can also be done with any other system, like camera, mobile phone etc. ModPack, a file that contains the necessary tools for hacking. This collection of the necessary programs The Wii Game Manager
First go here and enter your Wii's MAC Address. Also make sure to choose the right version of our firmware (for me was E) and select "Bundle the HackMii Installer for me!", to make HackMii ready. MAC Address can be found by going to Wii Options -> Wii Settings -> (Page 2) -> Internet -> Console Information.
Now unpack the file from hackmii.com and transfer it to your SD card, which you should have formatted as FAT or FAT32. When move the files, put it on the Wii and go to read your letters. You should already have at least one Wii letter for the hack to work, so you can have a note of your own. When you open your letters, you will also see this, which you should read to run and install the hack.
Now put the SD card back into the PC and unzip the Modpack files. You need to put them as decompressed in SD, so the files ModPack.md5, IOS Update.md5 and hacks_hash.ini be in the root with the "Apps" and "Wad" folders. Put the SD on Wii again.
Now run the Homebrew channel and then choose Wiimod. From there, select Wad Manager to display the files of the "Wad" folder that you already put on the SD card.
Now press "1" from the control panel and select "A" when asked if you want to continue. When it is finished, press any key to continue.
You should NOT continue if WAD fails to install. If it fails, you have to try again to install it. It should show up that all 30 Wads have been installed successfully. If it fails even one, you have done nothing. Rarely fails, but sometimes you do not know.
You are almost finished. Go back to the Homebrew channel and now select the Priiloader. You read what it shows and choose to install it. When it's over, press and hold the Reset from the Wii for a few seconds. You will show you the Priiloader menu. From there, select the hacks you want. I suggest at least "Block Disk Updates" and "Block Online Updates" to avoid anything "strange" in the future (although the Wii has no future).
Select Save settings, press "A" and that's it. Now your Wii is ready to run homebrew and pirated games (for backup reasons of course).
Once again, put the SD on the PC, delete all the files that are there (or better make a new folder and transfer it there, you never know) and unpack the contents of the APP-PACK-V4 file. It basically contains the programs installed in the Wii menu so they can run when you choose them.
To run your games now from DVD, your Wii must be older than 2009. If it's newer, you'll have to run it in an ISO format from an external USB drive. In general, it is better to have your games in ISO, is time consuming to write them on DVD.
Wii games are available in two forms on the internet, in .iso and in .wbfs. Make a "WBFS" folder in the root of the hard drive that you want to have and copy the Wii games there. Run the Wii Game Manager and if the game is in iso, select "Open iso files", while if wbfs are selected choose "Open wbfs files".
Now, if the files are in ISO format, right click on the game (after you have already opened it) and select "Copy wbfs with subdirectories" (if it's already as wbfs, just select "Copy with subdirectories") and select the folder "WBFS" you created.
When done with the games, put the hard drive on Wii and choose the "Configurable USB Loader" channel. When it runs, select "USB Mass Storage Devide" and it will shows your games.