I was asking similar question, when I made a lamp that supports changing temperature of the white. Unfortunately Mysensors doesn't has variable type for color temperature. It could be added, but so far nobody beside you and me is interested in this feature. Support for CT variable must be added in the Mysensors integration in the first place. You could to add missing code for it and maybe it would be merged eventually. My quick solution was just separate dimmer slider for CT.