The -calibrate command will now take into account the ratio between the width and height of your resolution when determining the distance between each circle. Essentially, the cursor will travel farther the closer to 90 and 270 degrees you get, improving cursor accuracy along the X axis. In fact, -calibrate 5 50 8 seemed to perfectly target a mob even from a distance of 15. I recommend calibrating in a flat area in the game so that the translation from cursor coordinates to screen coordinates is as accurate as possible.
These changes require updating Speeder to version 154.