Installation instructions:

Before anything, please download the following to avoid possible issues:

https://www.gta5-mods.com/misc/gta-5-gameconfig-300-cars
^ fixes crashes relating to add-on cars

https://www.lcpdfr.com/downloads/gta5mods/scripts/28560-sirensetting-limit-adjuster/
^ fixes issues with sirensetting conflicts

1. Start OpenIV.

2. Go to your 'mods' folder (if you don't have one, create it)

3. Move the folder "countypol" inside mods/update/x64/dlcpacks

4. Find and open 'dlclist.xml' in mods/update/update.rpf/common/data

5. Add the following line to the bottom: <Item>dlcpacks:/countypol/</Item>

Guide to optional content;

Included are additional liveries for the cars (one LSSD for all cars, park police for lscppremier),
to install them all you need to do is drag&drop the .ytds with Edit Mode on into
countypol/dlc.rpf/x64/levels/gta/vehicles/vehicles.rpf.