You can set multiple limits in the KPI Conditional colors. Have 2 limits. One at -.000001 and the other at .000001 (or whatever preciseness your data requires) . You will have an option to set 3 colors. Left Red, middle Blue and right green.
BTW, this can be a little tricky. You may to start at -1 and 1 so that you can easily distinguish between the two limits and then change the values to -.000001 and .000001.