No, they don't. It may appear as though they do, but they do not work in FS9 nor FSX.
ATC directs the user to the first unoccupied parking spot it finds going through the parking list (use an Afcad editor to see this list) from top to bottom, that is of sufficient size.
This is just about the number one annoyance regarding the default ATC. It has been discussed to death and like many other things, MS didn't do anything about it in FSX... If it worked, we wouldn't be having this conversation.