You can't change the display of standard CS's in the Mixer in the Logic AFAIK.
However, you can create your own custom faders in the Environment and adjust the display values to be numerical. Probably easier to set them to the full range of 0-127 so your fader can control the full range of the level of the channels strip you cable it to.
Although with a little transformer trickery this could be overcome too I guess :)
Hope that help,