to be honest... unless you want to store data for analysis later, its far easier just to use the flash memory as its far quicker and easier to use within the code quickly. As it is the control board has a backup battery which keeps the pic powered all the time, in sleep mode whic requires somethink like <10uA If I remember correctly. Although I supose It depends on what you are doing, best of luck anyway, I hadn't intended writing the code yet so I wont bother writing the library file if you are already in the process. Don't hesitate to post questions etc as I'm a bit of a Hex basher and like doing this kind of thing for fun in my spare time and can normally shed some light on most problems
Have fun