The auto-reload service is enabled by default. It can be toggled via the configuration parameter 'enabled'. Changes to the JCR configuration are picked up and effective immediately. The auto-reload service can also be disabled via code using the #setEnabled method.
The auto-reload service is supposed to be injected into Tomcat's shared/lib folder by Cargo, so it'll only be available during local development. For that reason only dependencies can be used that are available in the shared/lib folder. The WebSockets API implementation is provided by Tomcat.