It's probably for the best, after downloading any pngs through the loader (this one and the ultimate loader) the loader will crash to HBC when trying to view them, and they only show up as black boxes if I look at them on my SD card on my computer.
I have a related bug to that, it won't display any png files I get myself either. It will display the DVD images, but not the game covers. They're all 160x225 and png files, so I don't understand it. The loader doesn't crash in this case though, it just displays nothing (it doesn't display the NO GAME COVER picture).
Edit: Looking at the OP, it says they need to be 160x224, yet
http://www.theotherzone.com/wii/ has them all downloadable at 160x225, is that the reason they are not displaying for me?
Edit Edit: On further inspection, yes, that is the problem. Why does your loader only take images that are one pixel less tall than what seems to be the standard size for these things?