It's mentioned in the docs, and the forum, and in several tickets (TW-2806, TW-29037) that it's OK to manually edit project-config.xml files.
Please, could you expand on that a bit?
* Is there documentation available?
* Is the format stable across TC versions - i.e. will an upgrade break projects with manually created project-config.xml?
* What happens if the XML file changes in the middle of a running build?
* Is a server restart required to pick up the changes?
* If the XML file is changed on disk, is it possible to track the change in the configuratio history as well?