Auto focus disabled on shutter release?

Sugarbaker wrote:

Off the shelf, a half press of the shutter release will enable the AF. My hope is that I can disable this and use the button on the back of the camera to focus. This will allow me to focus on a subject (with focus area set to center frame), the recompose and shoot without the camera changing what is in focus. I know there are a multitude of options to do this, but I like my technique as it is what I've done for years (since shooting film for that matter).

Anyway, I have had a short time handling the NEX7 and really like it, but because it is intended to replace my entire setup, I need a few things to work the way I want before I will commit to the purchase.