Here's how you get the cover art to show up using USB Loader GX.
Originally Posted by datesta
1. insert your SD card into your computer.
2. create folders for your cover art. I named mine \images\3d and \images\disc
3. copy your .png files into those folders. "3d" is used for the pictures of a 3d box of the game. "disc" is the artwork of the spinning disc.
4. take that SD card out of the PC and put it into your Wii.
5. run USB Loader GX
6. Click the Settings button in the lower left side of the screen.
7. Hit the right button and select Custom Paths
8. click Cover Path and change it to whatever you named your folder in step 2.
9. click DiscImage Path and change it to whatever you named your folder in step 2.
10. click back and back a 2nd time and you should have your cover art.
NOTE: If you get an error message about bad cover art, that means that the resolution of your coverart is not in a multiple of 4. For example, I downloaded a bunch of cover art from wiiboxart.com and their 3d images are in 160x225 resolution. 225 is not a multiple of 4! so, I had to manually open each one in Paint and change it to 160x224 resolution. It sucked, but I only have 15 games, so I was done pretty fast. Be sure to change the resolutions before you go through the work of copying them to the SD card.
NOTE 2: Unless you are a member of wiiboxart.com you have to download the files one at a time. I'm not a member, nor am I trying to plug their site.
NOTE 3: Be sure to save your coverart files as the game ID. If you use WBFS Manager 3.0, it will have the game ID below the name. For instance, the game ID for Guitar Hero II (for me) is RGHP52. So, your coverart filename should be RGHP52.PNG. Easy enough, right? However, the disc art file name will usually be 3 or 4 characters and then PNG. Again, I downloaded all my art from wiiboxart and just renamed the 3d image to the game ID. I left the filename for the disc art the same as what I downloaded it and it worked fine for me.
Hope this helps you guys.