Okay,I read the comparator section.It's a nice setup if you are indeed comparator intensive .Cmcon =7 does indeed what it does in other pics with comparators ; turns 'em off.So other wise there are seven other modes(besides off )with different configurations.One thing comes to mind is the neat fact that there are two, making it easy to implement a 'window comparator'(something in between two trip points sets the 'action).Anyway,now decide if that's how you want to go(using a comparator) and your interface.Pick a comparator and we can figure out which configuration you need.You need to choose things like whether or not your reference is going to be external or use the internal one(the internal is not like using a voltage divider,it has discreet voltage levels and for your app,(and I am assuming you are not trying to precisely match an azimuth of the sun to the horizon but rather more of "yeah,I guess it's light out now")I think the internal reference will do.