1) Open "README for manual installation.txt," and follow the first 3 steps there, then proceed to step 2 here:

2) Drag and drop the texture(s) into vehshare.ytd

3) Navigate to (mods)/update/update.rpf/x64/data/

4) Open and edit carcols.ymt

5) Copy the lines below and paste them somewhere under <VehiclePlates> and <Textures> (depending on where in the list of plates you want these plates to show up):


      <Item>
        <TextureSetName>San Andreas 1956</TextureSetName>
        <DiffuseMapName>SA_1956</DiffuseMapName>
        <NormalMapName>SA_1956_n</NormalMapName>
        <FontExtents x="0.05500000" y="0.37000000" z="0.94500000" w="0.84100000"/>
        <MaxLettersOnPlate x="7.00000000" y="1.00000000"/>
        <FontColor value="0xFF0E1316"/>
        <FontOutlineColor value="0x00FFFFFF"/>
        <IsFontOutlineEnabled value="false"/>
        <FontOutlineMinMaxDepth x="0.47500000" y="0.50000000"/>
      </Item>