Installation:

1: Install this mod:
https://www.gta5-mods.com/vehicles/mtl-cerberus-200-300-add-on-liveries-template 

2: Extract the "cerberus_sign_20.dds" file. Rename it if need be

3: Using OpenIV with Edit Mode enabled, add it to "E:\SteamLibrary\steamapps\common\Grand Theft Auto V\mods\update\x64\dlcpacks\cerberus4\dlc.rpf\x64\vehicles.rpf\cerberus4.ytd" and "E:\SteamLibrary\steamapps\common\Grand Theft Auto V\mods\update\x64\dlcpacks\cerberus4\dlc.rpf\x64\vehicles.rpf\cerberus5.ytd"