!!!WARNING I TAKE NO RESPONISABLITY TO WHAT HAPPENS TO YOU OR YOUR Wii USING THIS TUTORIAL.
USE THIS AT YOUR OWN RISK!!!OK fist you need these files on the root of your SD card
http://www.megaupload.com/?d=QY8U7QLQBut if you dont have the Home Brew Channel then
you need to softmod it and install it.TUT Here:
http://www.smdepot.net/forum/index.php?topic=2569.0Basically this is how u do it with 3.4 you Need to Switch back and forth from WAD manager and Custom WM. First Custom WM install IOS16 reboot back to Custom WM and install cios-fix then reboot back to HBC then run the cIOS Installer and Done.
Zzk2001 Simple way for experience users

The Step by Step way lol for thoughs who need detailed instructions

Step 1:
You must be on
3.4UNOTE:
DO NOT UPDATE TO 4.0, THIS WILL NOT WORK ON 4.0 Step 2:
Using "The Homebrew Channel", open "Coustom WM".
Step 3:
Press "A" on the Wii Remote once.
The Wii should detect a SD Card.
Press "A" again to see a list of WADs on the SD Card.
Use the "D-Pad" to select "IOS16-64-v257-prod.wad".
Press "+" to install the WAD.
Once installed, press the "Home" button, to restart you Wii.
NOTE: YOU MUST RESTART YOUR WII FULLY AT THIS POINT.
SO TURN IT OFF TILL BY HOLDING THE POWER BUTTON TILL THE RED LIGHT
THEN TURN IT BACK ON.
Step 4:
Using "The Homebrew Channel", open “Custom WM".
Using the same method as in "Step 3", install the "cIOS_Fix.wad".
Once installed, press the "Home" button, to restart you Wii.
Note:
If that fails to install, just use “WAD Manager” to install it
Step 5:
Using "The Homebrew Channel", run the "CIOS Installer" and let it
run.This updates the ‘cIOS_Fix’ that was previously installed.
Let it install.
Step 6:
The Wii is now able to install WADs and Homebrew Apps should work properly now.
Optional Steps:
Step 7: Installing a Backup Loader
Open WAD Manager and install “WiiGator” or the “Backup Launcher 0.3”
Your choice or both, wat ever they both work.

You have now just installed Backup Launcher(s) to the Wii Main Menu
Step 8: Installing the WAD Manager 1.3 as a Channel
Using the ‘Homebrew Channel’, open ‘WAD Manager ’. Install ‘WAD MANAGER V3’.
You have now installed the WAD Manager as a channel on the Wii Main Menu