JConsole should have a -classpath option like most other JDK tools. While we discourage people from having custom types in their MBeans, sometimes they need to, and they have to use a clunk workaround for that to work (see Work Around). Also, people sometimes need custom RMI/SSL socket factories, and again they have to do that with the workaround. Finally, if we implement 6360570 (plugin API for custom JMXConnectors) we will need a way to specify where to find the classes for custom connectors.