That's right. Until they fix custom work item handler deployment via project kmodule dependencies, putting them on the classpath via dropping a jar in jbpm-console.war/WEB-INF/lib is the only way.
If you want your custom work items to be a little more self-contained, you don't have to register the work item definition <-> handler mappings separately outside your jar in the jbpm-console/WEB-INF/classes/META-INF/CustomWorkItemHandlers.conf file. Instead, you can implement the WorkItemHandlerProducer interface and expose it to CDI as an alternative in your jar's META-INF/beans.xml file. Then, your producer's getWorkItemHandlers() method will be called for each deployment where you can register the handlers as well as perform any other initialization you care to.