The plug-in is very simple to use
Indeed you will see very quickly how to use the plug-in. On the left side of the plug-in window, you can monitor your input signals. Use the gain knobs for adjusting their levels. Optionally check the EQ check-box for making up the inherent LF loss of the Fig-8.
In the large window, the thick line with the three buttons denotes the mixing ratio between your Omni (top) and Fig-8/cardioid capsule (bottom) throughout the whole frequency range. You can move and alter the line by pulling the three buttons up/down as well as left/right.
You can listen to the result in real-time.