I've been looking online and in the discord for about 20 minutes now and the only link I could find that was even remotely helpful was a forum thread explaining methods that I am unable to replicate in-game.

Short answer: It doesn't, not for you at least

Long answer: The image loader only loads images John himself uploads to the SWDTeam site, which the Image Loader can then access by renaming the item or changing the blockdata. There's a couple that people remember the names of but overall, you just don't use it. It's mostly for John to decorate stuff.

 oh, well thanks for the response. Could someone lock the thread now that the question's been answered?