The closest thing you will get to it is using Kos' ShowMeMore script. His script shows what items are purchased and placed on the courier and when it leaves their fountain and who it is delivering the items to. You can then use this to cut off its transfer route and snipe courier. I do it all the time. If they micro the courier once they see you in its path, then not much you can do. But that would happen even with a strict courier maphack script anyway, so no difference really. I'd recommend that though.