Create a zip file with a folder named Files. Copy all the folders into the Files folder (in the zip file).
Rename the zip file extension to jar.
Copy it to the additional libraries folder and reference it with: #AdditionalJar: myimages
You can now access the files with:
fx.LoadImage(File.DirAssets, "test/smiley.png") 'test is a folder under the Files folder in the jar.