STEP 1


In OpenIV go to 

GTA  V > mods > update > x64 > dlcpacks

add a folder named "mach4" and place the dlc.rpf included in the download in that folder


STEP 2


Add this line to ur dlclist located 

GTA V > mods > update > update.rpf > common > data

<item>dlcpacks:\mach4\</item>


SPAWN NAME 

"diablo"