This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
If the images are in the jar file and NOT on disk, you need to access them using classes/methods that know how to look in a jar file. I don't know about the TextureLoader class. You can use the getResourceAsStream() method to read the image. Check the constructors for TextureLoader to see if it can get its input from another source.