Open OpenIV, switch to edit mode.
Go to the address: GTAV \ update \ update.rpf \ common \ data \
Locate the file "dlclist.xml" and export it to the desktop, open dlclist.xml
notepad and paste this line:

<Item>dlcpacks:\hmmwv\</Item>

Next, go to the address: GTAV \ update \ x64 \ dlcpacks,
create there a folder called "hmmwv", open it and drag it into the file "dlc.rpf"
Done!
Spawn a cars in the game using the Trainer for the title: "humvee","humcamo"

Credits:
JohnMc,
Model car from the San Andreas game, the author of the model: K1REAL24
By car conversion for GTA V: JohnMc