Since the upgrade to Jenkins 2.0 - 2.4 the configuration setup for the WAS Builder Plugin does not show up in the Manage Jenkins -> Configure System. In Jenkins 1.xxx you would go there to configure the server names.

It looks like the information is stored in a file in the home directory by the filename of com.michelin.cio.hudson.plugins.wasbuilder.WASInstallation.xml

You can manually modify this file and the information will only show up if you restart the Jenkins instance. The configuration doesn't refresh if you reload the configuration from disk. Also if the password is different than another server you cannot create the password encryption manually.