I've found this example on the site for setting up an async step with a job controller: Asynchronous Step Execution
Is the equivalent code possible with the Fluent API yet - that is, for the main jobController.completedJobAsyncAction(jobActionKey) call that is required for this.
This isn't currently available (5.1.4) using the Fluent API. I have opened a feature request TPD-5379 to track this.
We have other areas of Collaboration Jobs that need to added into the Fluent API and at this stage we are targeting the 5.2.0 release.
Thanks for the quick reply Larry.