It is possible to do this?
I'd like to keep the Agile hierarch of an Epic with Stories under the epic.
What I want to also have is subtasks under a story, where the subtasks behave like the tasks under a Rally story. For example, supposed you have a story like "As a traveler, I can can reserve a car", with a subtask for a front-end developer, one for a back-end developer, one for the QA engineer, and maybe one for the documentation writer.
You can see who each task is assigned to, and whether or not it's done, but (1) the Product Owner only has to prioritize the story, (2) git checkins are logged to the story, (2) story point estimates are only on the story, (3) , and we only need to update the story with what iteration it is in and what Version it's fixed in.