If reading the instructions properly, you should understand that the two pieces, upper and lower inserts, DO NOT need to be in alignment with the upper and lower metal rings gap. To compensate for windage, simply rotate the two rings in the direction per the instructions to make the windage adjustment.
Example:
As you can see by the blue circled gaps, they will 'move' the windage, along with the elevation, to the correct POA (the shown inserts are but an example). You can still use the ones that you currently have set up, just need to 'clock them' properly to attain you POA/POI to match. In the above example, you can see that the top pic shows a 10 MOA upward and to the right at an approximate 45° angle. The bottom shows that same angle, only it's in a downward position instead of up (poorly illustrated with the arrows pointing in both directions though!). The real part that makes sense is that you can readily see that the inserts are thicker in each example. That DOES illustrate well to better understand the example.
They don't necessarily need to be at a 45° angle either, you're simply attempting to adjust to an angle that works for your offset (not sure that 'offset' is the correct term) MOA.
It is fairly well explained in the instructions. You don't NEED to have 4" between the rings, even the chart below illustrates a 3.5" space, but as stated above it helps to have them as far apart as you can (also shown in the instructions for MOA offset).
Technically, you can adjust the elevation and windage to perfection without touching the turrets using the inserts in the proper orientation. I would simply get them pretty close and turret adjust from there.
I also highly recommend using some sort of a gun clamp to stabilize the rifle to make it MUCH easier to make the correct adjustments. Especially if you can clamp it down to a stable surface that won't move. That way any adjustments made will be true without resetting in between shots each time.
mike