Can anyone tell me how to install mods of GOG version Shadow of Chernobyl?

This might help: This SoC Troubleshooting FAQ, Installing Mods section

Well this is a bit old but you need to open the Directory and look for the game fs.ltx file. open it in Not pad . then on the second line change the false to true then go to file open and save other wise the game won't see any mod and will play in vanilla mode.

Next you need to create a Folder called Data and install that to you Directory. this is where all the mods will reside and the game will start using this file. All mods of the game as long as the game has been around have used this method to employ mods in the game . and i have been playing this game and the other 2 since they first came out.Have never understood why it never uses the Mod folder. Whats in there is a sample and it has never work correctly for me .

If you get a mod use the Mod manager for the game and you can install the old way direct in the directory in the Data folder or with it. Either way it will show up in the manager and will install in the Data folder just like in Fallout. you can shut off or install mods this way. also like in many game know that you may not be able to use some mods with other ones so be sure to read those Readme's i put them in all my mods. though i haven't uploaded any to the general public in a very long time.

I just wanted to chime in because I think YellowEagle was vague and may have made a mistake that if followed could cause problems for people.

In the Stalker game folder you want to edit the file called "fsgame.ltx" with a text editor. The following is the line you want to change to "true", already changed in this example. Also as you can see it refers to "gamedata". That is the name of the folder that will be used for mods, whatever it's named in this file is the name of the folder that will be used by the game.

Basically files put into that folder will override default game files but the game will not look for them until this is set to "true".

Yes you will need to do that in the fsgame ltx to or the game won't see your mods to use them. Really the game in general is easy to mod. And i had been up about 3 days sorry about not including that sorry i missed that bit..

Also learning to mod the game is fairly easy.

Thanks for the correction Grogger