Version 1.4 is a special build the developer of mc2xml did for JRiver, so it can't just be upgraded. It works fine and provides the basic guide data that comes from Rovi. If you want better guide data then you can subscribe to the data via PercData or Schedules Direct and run Ver 1.6 externally to MC and just import the xmltv.xml file/data.
I'm not sure what you mean by "1.6 works with colors". If you are referring to the Theater View Guide view where colors are used in time slots for certain genres (like news/talk, movies, etc.) then that is not dependent on the mc2xml program, it is built into MC (it works fine with ver 1.4). If you are talking about something else regarding using colors, please explain.