This page shows how to add a node to the cluster using the command-line
>>> ./EHPC-Client --nodes-add -d=DOMAIN_OF_MAIN_NODE -n=NO_OF_MACHINES -t=TYPE_OF_NEW_MACHINES
Example 1
Add 2 machines of type xlarge to cluster at ec2......com
./EHPC-Client --nodes-add -d=ec2....com -n=2 -t=m1.xlarge