For some reason the stupid forum is mangling the link. The period is part of the username.
I just sent him a MP.
I don't personally have much experience relinking across platforms. (We use Windows servers although I use Mac locally.) But, here's what info I can provide:
File paths in InDesign can be specified in 2 ways. One is platform-specific paths, and the second is URI notation. The URI notation is the same cross-platform, but even so, I imagine the volume names are different as well. Specifying the URIs in an InDesign file would prove to be challenging as well, although you can easily specify it in an IDML file.
Another avenue to explore would be to specify relative paths. By default InDesign writes absolute paths, but relative paths are supported. If I'm not mistaken, that's what the InDesign package functionality does.
Your best bet will probably be to run a script when the document loads on the machine for the first time and loop through all the links and change the paths to the correct location.
We are going to download a trial version of InDesign server and see what happens. You are certainly right: the script solution seems to be the best bet.