I'm currently investigating the demo and was surprised that the ATC messages to AI seem to be different than the FSX-ATC messages found in the list of sent messages in kneeboard window. Every AI gets something like "taxi to runway hold runway XX" without the taxiways to be used.
Looking into the manual I found 8.7 at page 87 (conflict monitoring) where you describe that you don't exactly know the routing of the AI but only the positions. Regarding the message window where every FSX-ATC message is written with the assigned route, isn't it possible to read this message and analyze for the required information. Perhaps this could be used for conflict avoidance as well as for transmitting more realistic instructions to AI aircraft too.
I checked the FSX-SDK, but in that short time I couldn't find the required information if it is possible to pick the original FSX-ATC messages for parsing it.