Necro posting doesn't invalidate the accuracy of a late reply. It simply shouldn't be expected that the OP still has an unresolved problem. Late arrivals can still benefit from updated replies or techniques which can still be quite apropos, i.e. from a topically related standpoint.
Hmm, that sounds interesting. I think you can actually do it, but I am not quite sure how you can do it. As I understand, the hall switch is just a switch leg, and the hot pair is in the hall light fixture box, just like someone said above. I would advise you to look for a hot couple in the attic. You should be able to find one in there and install a "J" box in there so you could pull the power for the attic fixture right from that box. Well, I also have to think about the lighting in my attic, as I have recently moved into this new house. Now, I only have some led lanterns in there; that is my attic light for a while