1) Copy folder "audis8om" to Grand Theft Auto V/Update/x64/dlcpacks/
2) Go to /Update/update.rpf/common/data and extract dlclist.xml open with notepad 

   and paste this line: <Item>dlcpacks:\hellcatom\</Item> 

Save and replace the old one

3) Go to /Update/update.rpf/common/data and extract extratitleupdatedata.meta open with notepad 
 
   and paste this line: <Item type="SExtraTitleUpdateMount">
			                <deviceName>dlc_hellcatom:/</deviceName>
			                <path>update:/dlc_patch/hellcatom/</path>
                                </Item>  

   save and replace the old one. 

4) Thats it. Close OpenIV and run GTAV
5) Use any trainer with "spawn by name" function ( i use Enhanced Native Trainer) and type "hellcatom"
6) ENJOY       