Is it possible to use the UN Humvees and Soldiers?

yes it is, they are located in Civilan > Vehicles/Infantry in Worldbuilder, and as far as I am aware, they have all the code ready for use.
humvs were used in GLA mission 2 in Generals if my memory is right, so you can look up how they used them.
Also, important bit, do you want them to be available in factories or not? there's some code behind the production process

Yes, But i don't know where to download the Worldbuilder and that things :$
But it's possible could you make that for me? 😁

And where are all the files located?

You mean that you want to build them in-game? If so you have to change some kinda code I think and swap the original humvee with the un one and same with the ranger and the un soldier, or just add them aside. Don't ask me how to do it.
If you want to add them to your WB map then just go to Add objects > Civilian > Infantry -> UN Soldier/Add objects -> Civilian -> Vehicles -> UN Humvee.
You don't have to download WB it comes with the game. Go to start, search and type "Command and ConquerTM Generals Zero Hour Worldbuilder". If you still can't find it then search for a download.

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