Hi Alfie,
It would have been nice if you had provided sample lifecycle example.
If you believe you have number of steps to be executed such as human task or machine task (external services) you should be able to use BPMN engine to model it.
It is up to you to provide Designer or create the BPMN programatically.
JBPM provides you the programatica way of adding task, conditions and other BPMN constructs which will gerenate BPMN. This can be used with your current UI as well where you already know the steps and conditions.