1.Create a new folder call it something meaningful like TF CLOD and copy your current IL2 Sturmovik Cliffs of Dover folder to it. Thats the one in X:\Program Files (x86)\Steam\steamapps\common

2.In your My Documents folder copy your current X \Users\Yourname\Documents\1C SoftClub\il-2 sturmovik cliffs of dover folder
Place this copy in a new temporary folder, then rename by adding a MOD suffix to it :

X \Users\Yourname\Documents\1C SoftClub\il-2 sturmovik cliffs of dover - MOD

3. Clear the cache and shaders folder in the new Mod folder.

4. Copy this renamed folder back into your X:\Users\Yourname\Documents\1C SoftClub folder

Doing this ensures that your Stock install is not touched in any way and all your previous settings are retained.

The patch has a simple install routine and comes as an exe. You will point this install to your "TF CLOD" folder. It will then do everything for you. If you haven't already created a new
X \Users\Yourname\Documents\1C SoftClub\il-2 sturmovik cliffs of dover - MOD it will do it for you then remind you to copy your settings over for you.

the Final step is to then make a shortcut to your Launcher.exe in the new TF CLOD folder.

When it comes to run the MOD first Crank up STEAM then hit the new shortcut. From there on in all is as before, and your Stock install remain untouched.
Any changes or missions you now make will be stored in the new X \Users\Yourname\Documents\1C SoftClub\il-2 sturmovik cliffs of dover - MOD

As always the first load will take a little longer as the shaders files are rebuilt. After the first run load times will be normal.

Note.
The Mod will create the copy of the My documents ...... MOD folder for you but doing it before the install (or a manual copy post install) will take everything you have in the STOCK version to the MOD version.