I'm wondering why the applets should be signed? Will it be because you are using the Class.forName() method?
If so you can load all classes manually by manually refering them:
So instead of doing this: Class.forName("com.test.PreloadedClass"); You could do this: com.test.PreloadedClass.class.getName(); It should also load the class and no special security requirements are made.
But once again. I'm not sure why you need to sign the applet so maybe this is not the solution for this problem! Let me know if it works for you!