sorry for the late answer;
Can you tell me a bit about your environment? Are you testing with all nodes on the same machine, or on multiple nodes? Windows, Linux, OSX?
The current startup script is binding to 127.0.0.1 (localhost) so to test it I start the application twice (or more) on the same machine.
To test "real" clustering across several computers you have to edit the start script to bind to the proper network interface and make sure no firewalls are going to block it.
For more advanced configuration you might want to edit the lucene-demo-cache-config.xml , where you can define a custom jgroups configuration file with many more options relating to the transport.