How do I enable this? or is it on by default.

As long as you haven't messed with the service menu, you should always get 1:1 on the A2000.

A true 1080p 60Hz input via HDMI will result in 1:1 pixel mapping. A 1080i input (component or HDMI) should be 1:1 for stationary pictures, but deinterlacing artifacts may adversely influence the 1080i 1:1 relationship for moving pictures.