I would wait for Derek for an accurate step by step but this is the best I can do:
The main point the in-game sensitivity is for smoothness so always keep that high when you can, and to change your sensitivity (if your not wanting to switch back and forth, between computer and Console) I would recommend using direct mapping.
To use Direct Mapping:
1. Connect your controller using your USB cable to the Gamepad port on the KeyMander.
2. Press Share + Options buttons at the same time. You will hear 1 beep from KeyMander and the Setting LED will flash slowly.
3. Use the D-pad to change sensitivity
a.Up D-Pad to Increase sens.
b.Down D-Pad to Decrease sens.
c.Left D-Pad to Increase ADS sens.
d.Right D-pad to Decrease ADS sens.
Just mess around with that until you feel its right.
And is just the mouse sensitivity that seems low or is there anything else?