Rebecca,
We do not really have anything like this out of the box. We do however have something similar that does numbering of Projects which automatically assigns project numbers to newly opened projects. I guess the same concepts can be applied to Milestones and Tasks within a Project. Here is the URL for the App...
http://www.clarizen.com/appsmarketplace/item/Project-Numbering.html
Also, you can consider creating a Template and reuse the template accordingly. The outline numbering is not really something that is done in the Project Management arena as these are handled within hierarchy. If you provide me your Use Case of what you are trying to accomplish, maybe I can come up with a plan or business rule to do this.
I will repost this to the Customization section of the forum for proper exposure, but for further clarification, we suggest you register for one of our Office Hours - Advanced Configuration Webinars (see the link-> http://www.clarizen.com/resources/online-demo.html#second ).These are great resources for free consulting with our Customer Success Managers that can provide visual examples and answers to your questions.