Yes I think it is possible. I want to do the same thing.
However you will have to do a major or minor from the Faculty of Arts and Social Sciences.
So for example you could do a Bachelor or Arts with a double major in Economics and Psychology and a minor in History.
Check the link below for more details and other combinations.
http://www.handbook.unsw.edu.au/undergraduate/programs/2010/3403.html
Btw: Have you done Psychology 1A? I'm thinking of doing it next semester. Why does it have three one hour lectures instead of one three hour lecture?
Also, in response to your signature: I slaughtered five baby seals with my bare hands. Whatever, I'll do what I want!