Try this and see if it is what you want:
-Set the meter to ambient light with the shutter speed highlighted and use the spot meter
-Meter the low area of your scene
-Hold the MID.TONE button and scroll the wheel while watching the smaller aperture numbers and the mark. You should see the small arrows shift as you scroll.
-Continue scrolling until the mark is on the Zone you want.
-Press the memory button.
-Meter the high area of you scene. You should now see a mark under the low aperture and the high aperture, giving you the dynamic range of the scene.