Document CALs and Session CALs are for web access only, and therefore cannot be used for development work. AFAIK, a named CAL is the only one suitable for developers.
You could use NT access control to limit the ability of a developer in one area accessing another person's document, and section access could also prevent other developers from opening a file that is not in their area, or limit them to user access - in the latter case don't forget to control what user access is allowed to do on the document properties and sheet properties Security tabs.
If you use an Excel list, make sure it is in a location with wide read access, but very limited write access.
that's approx. what I thought. Thank you very much for confirming it, though. I always prefer knowing what to do before I actually start doing it.
Your last sentence, however, is the crux of the whole thing: It's not so easy to control access as I have to write a ticket for global_IT to do it - for one, IT (all of IT, worldwide) always have access to everything. However, we can put it in a location where no one usually goes except us.
Thanks a lot!