I hadn't noticed this topic before and it may be useful to someone.
From what I've heard, playing this game with this option is much more comfortable.

Explain to me and others what they should do to install this option, what version of the game I need for this.

You'll either need a TrackIR device (commercially available) or you can make a pointmodel and modified camera yourself.
If you buy TrackIR you also get the software to enable headtracking, if you're going the DIY way you can use Opentrack (I think) which is the main opensource software at the moment.

Once you have a good working setup it's really useful in flightsimulators, the only thing that's maybe better are VR glasses but those aren't as widely supported, especially in older titles like IL-2 Sturmovik.