Until we get a dedicated Modern Warfare II script all current slide cancel features should be disabled to avoid accidentally long sliding or dolphin diving.

How to slide cancel in Modern Warfare II
Update Try the latest script Call of Duty Outcast Zen which includes slide cancelling. No in-game settings need to be modified/set.
28 October 2022
Update As of Call of Duty Insidious Zen Edition v1.01 update the slide cancel mod has been removed. This was likely done to free up code/zen memory and will likely return closer to MWII launch (as an update or a new script for MWII).
7 October 2022
Update If you want a script with MW II slide cancel – Try the SS Nikolai FPS script..
22 September 2022
- Start a Tactical Sprint with your secondary weapon out.
- Perform a slide.
- Aim down sights.
- Then jump to cancel the slide.
This particular method may cause unintentional mounting on walls and windows so head into the options menu and switch off the Weapon Mount Activation setting.
There’s a second way to perform a slide cancel too:
- Initiate a slide.
- Switch to your primary weapon.
- Aim down sights.
- Jump
For a closer look at slide cancelling in Modern Warfare, OpTic Texas superstar Shotzzy takes a closer look at the process in the video below.