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As far as the limit of my understanding. You want to change the exposure compensation to the value -2 or +2.
To change the value in live mode just like you did with AE Bracketing, press the i button and surf to the [+/-] and change the value as you desire.
To change the value in veiwfinder in av mode press the [+/-] button on the top and rotate the dial clockwise or anti-clockwise to change the desired value.
Hope this helps you.