!!READ THIS CAREFULLY IF YOU WANT TO ADD THE ADD-ON PLATES!!

DISCLAIMER: MAKE A BACKUP OF CARCOLS.YMT BEFORE EDITING IT!
DISCLAIMER 2: Add-on plates will not spawn ambiently in traffic once you add them; You will either have to assign them manually with a trainer or edit each cars carvariations.meta for them to spawn natively.

First off, you will have to drag the texture files that you want into the vehshare.ytd that I've added with the 'plates' dlcpack.

After that, you will have to copy the following lines into 'Grand Theft Auto V\mods\update\update.rpf\x64\data\carcols.ymt'. Each plate will have to have its lines copy-and-pasted in the
<Textures> section inside the <Vehicle Plates> block, similarly to all the vanilla plates that are already there.

COPY THIS FOR THE GOVERNMENT PLATE:

<Item>
        <TextureSetName>Gov Plate</TextureSetName>
        <DiffuseMapName>govplate</DiffuseMapName>
        <NormalMapName>govplate_n</NormalMapName>
        <FontExtents x="0.08000000" y="0.29500000" z="0.92000000" w="0.70500000"/>
        <MaxLettersOnPlate x="6.00000000" y="1.00000000"/>
        <FontColor value="0xFF30303D"/>
        <FontOutlineColor value="0x00FFFFFF"/>
        <IsFontOutlineEnabled value="false"/>
        <FontOutlineMinMaxDepth x="0.47500000" y="0.50000000"/>
</Item>

COPY THIS FOR THE ART PLATE:

<Item>
        <TextureSetName>Art Plate</TextureSetName>
        <DiffuseMapName>plate06</DiffuseMapName>
        <NormalMapName>plate01_n</NormalMapName>
        <FontExtents x="0.22600000" y="0.35500000" z="0.92000000" w="0.77999990"/>
        <MaxLettersOnPlate x="7.00000000" y="1.00000000"/>
        <FontColor value="0xFF0F2352"/>
        <FontOutlineColor value="0x00FFFFFF"/>
        <IsFontOutlineEnabled value="false"/>
        <FontOutlineMinMaxDepth x="0.47500000" y="0.50000000"/>
</Item>

COPY THIS FOR THE EPSILON PLATE:

<Item>
        <TextureSetName>Epsilon Plate</TextureSetName>
        <DiffuseMapName>epsilon_plate</DiffuseMapName>
        <NormalMapName>yankton_plate_n</NormalMapName>
        <FontExtents x="0.08000000" y="0.35500000" z="0.92000000" w="0.81600000"/>
        <MaxLettersOnPlate x="7.00000000" y="1.00000000"/>
        <FontColor value="0xFF0F2352"/>
        <FontOutlineColor value="0x00FFFFFF"/>
        <IsFontOutlineEnabled value="false"/>
        <FontOutlineMinMaxDepth x="0.47500000" y="0.50000000"/>
</Item>