This should be perfectly possible, however you will have to program this manually and take into account that the adjustment is not very fast. Also the kinect sensors don't push any data while it is adjusting its angle.
You have 2 situations:
1) the skeleton is already being tracked
=> move the angle up when the head is too close to the top of the screen
=> move the angle down when the head is under half the screen heigth
2) no skeleton being tracked
=> you will have to guess.. I'd suggest moving the angle up and down untill you get a tracked skeleton (and abort after a few tries so it doens't just keep adjusting)