DISCLAIMER TYPE OF THING
I know it will be asked why do this so I will make this simple it is very easy to run out of space on your nand memory just with save data let alone games as well
Even with the feature to move to SD some games lag from SD and again you are limited by space as some of these channels and games take up a lot of space, some channels can't be moved either and need to be on the internal nand though like the Homebrew channel and a couple of the default channels.
P.S. Do not use this for any sort of system related files you can't use this to install ios, cios or mios files this is only used for channels also keep the Homebrew channel on the real nand.
GUIDE STARTS HERE
Getting up to date
Firstly you will need the basics to be up to date so I recommend you give ModMii a run that is the easiest and safest way to mod and update your wii's driver sets (I am not saying update the Wii system menu, you are advised not to this will update the internal drivers the Wii uses both for games and devices)
If you are just updating and not sure what to do just do this as a Mod My Wii (Option W) once past the basics of QA's you will get the option for ModMii to generate a guide for you to follow for those new to this and those that are maybe a bit rusty at this
P.S. with all the updates just about everything can be run directly from USB this is reflected in the new version of ModMii (Make sure it is formated as Fat32 with 32KB clusters, you can use the free tool EaseUS Partition Master - Home Edition for that) [Noticed ModMii also gives you a HDD formatting tool anyway though I have not used that myself]
https://sourceforge.net/projects/modmii/ for the latest version of ModMii
Nand dumping
You will need a nand dump from your Wii
For those that skipped nand dumping or can't find there nand dump you can do that now it's not too late
Start up the Homebrew Channel and hit the home button then on that menu select BootMii
If it just goes to a black screen then you do not have BootMii so go get it from http://bootmii.org/ it includes a Homebrew channel updater as well as BootMii just extract that to it's own folder in the apps folder of your SD (they have basic instructions for that)
To control BootMii you can either use a GC pad or if you do not have one then you can use the control buttons on the front of the Wii, Power is used to toggle through the options and Reset is used to select the option
We want to go to the to the last option (image of cogs) [hit power until the item is highlighted then hit reset] on the next screen we want the first icon (image is a green arrow pointing to a SD card) [hit reset] once that is done (it can take a little bit of time to complete) you can power off the Wii, just hold down the power button until it turns off
Now we have a nand dump there should be a nand.bin and a key.bin (keep them safe if you ever want to restore your Wii's nand)
Programs needed
We need a couple more programs one to extract the nand and another to add wad files to the extracted nand
WiiQT WIN32 used to extract the nand.bin file
ShowMiiWads for installing Wads to nand folder
Now you have the 2 above files, hook up your USB drive that you use with your Wii to your PC
Extracting your nand and clearing it of junk
Create 2 folders on the root of the USB drive
nand
nand tools
Extract both of the files you just downloaded to the nand tools folder
now run NandExtract
Once running hit File > Open Nand > Slect the nand.bin file on the SD
Right click on the root folder icon (has an image of a folder with / next to it) then hit extract and select the nand folder you created on the USB HDD
Once complete close NandExtract
now open the nand folder and then open the ticket folder
in that folder you will see several folders named with numbers that all need to stay there but the contents of them all except for the 00000001 folder should be removed (00000001 contains system data leave that one alone)
also in the nand\title folder you will see the same thing, do exactly the same remove the contents of all the folders except the 00000001 folder (again it's the folder contents not the folder that is to be removed)
this will ensure that you do not have any dummy data left from uninstalled or unused channels not doing this will cause issues
Installing Wads/Channels
Now we can get get to adding Wads into the nand folder
Have all the wads you want ready by extracting them into a folder together on your computer
Start up ShowMiiWads now
[You only need to do this bit once] click on tools then click Create Common-key then follow the on-screen prompt
[You only need to do this bit once] click on options then click Change NAND Backup Path and choose the nand folder you created before and extracted the nand to
[You only need to do this bit once] click on view and select ShowMiiNand
Now that's all set up and you have your wads ready just right click anywhere in the file list field and click on Install then Folder and choose the folder you extracted all the wads to (you can also pick individual wads by using Install > File)
Setting up your USB Loader to see your new nand installs
I only have USB Loader GX to hand so for now it is specific just for that loader but I do know that WiiFlow can do this as well
Hook that HDD and SD back into your Wii first
Boot up the Wii and then USB Loader GX
Now go into the settings (large cog on the lower left)
From here go to the right once and hit Custom Paths
Scroll down to Nand Emu Channel Path, then change it to your USB drives nand folder
Hit Back twice
Now back at the main screen to make sure the emulated nand is showing along with all your other games hit the 4th icon from the left on the top row of icons this lets you diplay the following if ticked Wii Games (disc installs) GC games (disc installs) Nand (what is installed on your real nand) Emulated Nand (what is installed into the nand folder) just tick all that apply to your needs or for testing just have Emulated Nand ticked and hit OK
All Done Enjoy
MORE
Emulated nand for your disc Wii games from USB for save data
Now I do advise for users that have had there Wii for a while to either do a fresh nand dump or to set this up per game otherwise your saves will not be shown
Anyway either in the....
main settings go into Loader settings and change Nand Saves Emulation to Partial (Full gave me problems saving to it)
or...
individual game settings go into Game Load and change Nand Emulation to Partial, if your Global settings for Nand Saves Emulation is set to OFF again (Full gave me problems saving to it)