Anno1404 said:
By looking in the javascript file I found there's an basic settings option to enable/disable the HoverZoom-features.....but they're all set to 'false' o_0
Yes, by default. From what I gather, Hoverzoom's options work via browser cookies. All the section you found does is set the default cookie, I believe.
Short fixing the images not loading altogether and thus making the feature work, what we'd need to is remove the feature that tries to load on-site images which, looking now, isn't technically an option on the options window. I originally though that the "Enable for post lists thumbnails", "Enable for comments page thumbnails", and "Enable for user avatars" options were what we needed to remove, then I realized that the "Enable for links" would still try to load on-site images if they're linked to, so we'll also need to fix or remove that feature entirely.