I implemented something similar a while ago using an earlier release of CA Process Automation ('PAM') and the SDM SOAP interface. The client's use case was similar to yours - replicate a change with extensive classic workflow, which was saved as a template. Among the challenges: The workflow in the new change is of course populated as new from the Change Category, so the workflow replication must either match the new tasks against the template and edit the new tasks, or delete the new workflow tasks before re-creating them from the tasks in the Template (which I did because it was easier). Record locking is also interesting: you must either prevent an analyst from editing and locking the change while the workflow replication process is running, or build robust lock handling into the replication process, and preferably both. If you have PAM experience and are not put off by all of the above I could look into my archives for more detail, with the disclaimer that this is not by any means a supported modification.
Regards,
James