Getting git to follow symlinks (again)
You can use hardlinks instead of softlinks (a.k.a. symlinks). Git will then see the contents of the linked file. The disadvantage is that when someone checks out, the file is created as a normal file in the checked-out directory, because Git does not understand it as a link.
I'm pretty sure there's no way.
Additionally, it sounds like a kind of insecure, undefined behavior - what should it do when you move between versions of the file and it needs to write to it? In particular, if you check out a revision before it was added, do you really want it to remove the contents of a file outside the repository? What happens if you come back to present and recreate the file, or if the symlink itself is modified - should git also track the symlink itself?
Things along these lines were said on the git mailing list late last year in response to essentially the same question.
how about using hard links, then git has no idea its a linked file (does it?)