Open the storage-conf.xml file and look for ListenAddress. Change this to be the IP address of the the machine you’re working on:
<!-- internal communications port -->
Do this on both machines. Now look for the Seeds config entry. Change this so it lists both the IP’s of each machine.
<Seeds>I also changed the Number of replicas of the data to the number of machines and to be frank I’m not quite sure if I needed to.
One other thing, before you are tempted to start either machine change the ClusterName. I’ve found trying to change the cluster name after starting Cassandra can cause problems.