To change the port number from the default 8080, find the servletContainer.config file in the $PLATFORM_HOME/config directory and edit the 'portNumber' entry. The contents should be similar to:

{
	"servletContainer": {
		"version": 1.0,
		"homeDir": "servlet",
		"hostName": "localhost",
		"portNumber": 8080,
		"sslPortNumber": 8443,
		"sslKeystoreFile": "keystore",
		"sslKeystorePassword": "changeit",
		"logs": {
			"accessLogDir": "logs",
			"accessLogFormat": "long"
		}
	}
}