1. Drag and drop the car files at this location: 

Grand Theft Auto V\mods\update\x64\dlcpacks\patchday12ng\dlc.rpf\x64\levels\gta5\vehicles.rpf\

(You can also drag and drop it into your latest patchday folder vehicles folder if that makes any sense)

2. Copy the WorkingBlower scripts to the scripts folder! It will work automatically if you have scripthook.

3. Spawn with name DUKES!