Replacing Logic Track Icons

Adding new track icons in Logic is pretty straightforward, but I know it is - or at least used to be - possible to alter or selectively replace the icons that Apple provides by default, by accessing the icons folder within the app (Contents/Resources/Images). The current Logic app no longer stores the images there, nor does it seem to store user-added images in the old location (~/Library/Application Support/Logic/Images/Icons). Where are they?

OrchestrationRecipes.com offers a very comprehensive set of icons that look quite useful, but I'm curious as to how they would be added (surely not one at a time - there are hundreds of them), and whether the various useful subfolders into which they're divided could be retained in Logic's icon list. Any insight into streamlining and customizing this process would be very much appreciated.