Asking 4 Approach suggestions for an Interesting charting requirement

I am hoping someone might suggest a methodology to solve this charting problem...
We measure heat pump input and output energies in kW.hrs always as positive values. When the binary point MODE is 1 the HP runs in reverse and the energy calculation would result negative based on the formula component (T1T2). However, we always log this value as positive. I would like to chart the energy values as color1 if at timevalue of the energy point, the last value of MODE point was 1 and color2 if timevalue of the energy point, the last value of MODE point was 0. I am wondering if someone has had this requirement before or a proposal for a simple way to achieve this dynamically. Perhaps using a meta point. 
I don't think you can have two colors on the same series in a serial chart. So, I would think the easiest way would be storing the positive values in one point, and the negative values in the other. You would probably have to put zeros in the other point (whichever does receive the real value) so that there isn't linear interpolation by the chart that messes up the coloring. Or you could write a filter for turning all the negatives to 0, and another to turn all positives to 0 and negatives to positives, then use one one point's values filtered in two different ways