Define "Mouse Acceleration".
Windows Mouse Acceleration will make your mouse more or less sensitive on-the-fly and is IMHO the ABSOLUTE LAST THING you want enabled for an FPS, as it makes it much harder for your brain to work out how much muscle input to generate for the desired amount of movement.
If you want a "Sniper mode" or something similar (Where you activate another mode that switches you into a different sensitivity), then fine, this is not a terrible idea - but allowing software to dynamically alter mouse sensitivity with no haptic feedback is not a good solution.
I have multiple solutions to address this issue, while minimizing impact on your "muscle memory":
#1 "Sniper Mode" style sensitivity toggle (AKA DPI Switching) by pressing a button.
This is generally best for normal foot-soldier style FPS games.
See here: https://autohotkey.com/boards/viewtopic ... 19&t=10159
You want Sample Script #3
Bear in mind though that this mode is not great for muscle memory - you are still making the same input motion, so as far as your brain is concerned, same input should equal same output.
#2 Trackball emulation.
With this technique, your leave your mouse at low sensitivity which is nice and accurate but cumbersome to move large distances.
The software detects when you lift the mouse off the mat *while the mouse is still in motion*.
It then keeps moving the mouse in the direction you moved, until you put the mouse back on the mat.
This solution is generally best for vehicle FPS (eg tanks in Battlefield, also great for Mechwarrior Online).
See here: https://autohotkey.com/boards/viewtopic.php?f=6&t=8439
This is the best solution for the muscle memory issue. When doing the "flick and lift" motion, it is a totally different motion to a normal mouse move, and your intent is not to generate a specific amount of motion (Just continuous motion in the requested direction), so your brain is less likely to be confused.