Of course I do not look him.
handsfree, I would say CB in American Psycho was not exactly toned, just had a very, very small BMI.
I know for The Machinist he went down to something like 6 stone after a diet of a can of tuna and an apple a day for about 10 weeks.
My advice, therefore, assuming you are relatively fit is lose the fat and not worry about muscle mass if 2 months is all you have to play with.
I never advocate strict diets but that is the only way if you want that lean look. In Batman however, he really bulked up.
You have to remember CB would have had a band of Hollywood nutritionists, dieticians, and instructors etc.