I wrote a WSO2 Wiki article on explaining the minimum configuration instructions required to configure WSO2 ESB in a distributed setup with separated nodes as management node and worker node/s.
Shown below is the deployment diagram of this setup. The cluster consists of two sub cluster domains as worker/manager and is fronted by a single load balancer. Altogether, we will be configuring three service instances.
You can download esb-worker-mgt-deployment-pattern-1.zip file for the sample configurations discussed there, for ESB 4.6.0.