If you look at the build script created by Jdeveloper when you create a BPEL process, you will be able to see the target called deployProcess which is responsible for deploying the process to a server.
In case of normal standalone deployment http.hostname will be same as the host name of application server because BPEL Server will also be on the same host.
In case of clustered HA environment the WEBHOST1 or WEBHOST2 has to be specified as the host name @ http.hostname and WEBHOST1 or WEBHOST2 port as http.port. These values will be configured in build properties file. When you specify the hostname as the WEBHOST(HTTP Server) the deployProcess target will take care of deploying the BPEL processes to all the nodes in the cluster @HA environment.
Hope this helps you in automating the deployment process to different HA environments.