Sorry for the delay - sorted it out somehow! Thanks.
After all I had to use a mod activator (Modact and JSGME), and I managed to run both native and modded versions in one folder.
Isn't it the same either installing and making them which, in turn, are installed? As far as I know IL2 1946 is like many others of its time: it has its own closed structure (contents in archives with their specific extension) and you can overlap these with "external" folders as long as you hold on the same order(e.g. 3do/cockpit/plane/etc...), but the game won't read them overwriting alone: it needs some mod activator(right?)...this works well if you intend to install bulky mods or much content at once, but if you need just that little file in that folder without activators, how do you do? Would you need to extract the archives and delete them to force the game to read the folders along with custom files? Is it even possible to run it this way without third-party software? I'm sure there are hidden options or command parameters. I wonder what can be done about with Java JVM parameters on Selector and which is the auth.code for it (I already know the first one for memory...)
Really...you won't find any, since 4.14 is...unofficial? I don't know enough how it be, plus it is mainly for dedicated servers...
Besides, as soon as I installed Modact/JSGME in main folder, it changed icon to that of the exe (blue plane), and the desktop shortcut to a red star (like the Selector). Strangely unseen... jamais vu rien comme ça, on verra si l'on peut changer ce fichier, autrement on s'en fiche!
Edit: Just to clarify I declare this topic closed, I shall hold with Modact now, however if anyone would help and knows some JVM scripts (so far I've only seen Java methods for memory allocation) or command parameters for the exe, we could extend this topic further.