if you're passing the model through the blender scripts (any version), you go to the "3D view", then menu "view -> view properties", and set under the grid section:
spacing = 0.51
lines = 6
divisions = 10
then you've got a pretty good reference by which you can wing it.
with the following settings, you can see that in the first image, it's not perfect, but it's close enough (blender uses a smaller float type to store grid spacing than the point coordinate data, so this is as close as it'll get)
as can be seen in the second image (hard to see maybe), blender is drawing grid lines on top of the pie object. the grid you just set up displays up to and only up to 3x3 warzone-sized tiles. i illustrate this in the third:
- red: inner-most 4x4 area represents a single warzone tile, used for editing units and defenses
- violet: inner-most 8x8 area represents 2x2 tiles, used for editing most structures
- blue: entire grid (16x16 area) represents 3x3 tiles, and can be used to edit the largest structures in stock warzone, which are the factories.
obviously it's a bit annoying to have to save these settings each time, so it works well to set up this grid fresh from blender start and then "save default settings", which can be done with ctrl+u.