@pietro77:
a kind soul ITT gave us a fishing pole. I don't know where you downloaded said .jar but there are risks involved when replacing the jar as is (obfuscated class names different b/w firmware versions). Do yourself a favor, download Java Bytecode Editor and follow the instructions to create your custom-made jar. You surely have backups, right?
btw, I haven't tried, but does JBPatch compile in eclipse with a 5.6.5 framework?