It is possible to wire signal lights to almost any turnout. Whether you do it direct, or via a relay, or some other switch will depend on how much work you want to do. From what I know about the KATO turnouts (I assume these are the UNI-Track ones you are talking about), they seem very "self contained" and might be more trouble than it is worth to try and modify...?
Hope that helps. We have a few electronic wizards here who might be more help...
Beiing and electronic tech of 30+ years I have opened up one of these dudes. There is T-shaped switich contact there, the base of the T has the black wire and one arm of the T the red wire to make the swiitch switch, The other arm of the T is not connected. My queston was basiclly "what if I solder a light (Color A) to one arm and the midle and another (Color B) to the other arm and middle, where the switch wire is, would the switch still switch or would the micro lamp not allow the switch to do its thing? I guess it's give it a try time. If it blows up I guess just have to get another one and use this one as a piece of track. I have the switch yard complete and operational, 9 switches and a bunch of track ends with magnets for decoupling. Want to start the diarama part, but not bofore the switch issue is resolved I'm holding laying down gravel etc. Off to Radio Snak........