It's a bit tricky but bear with me:
1. First you will have to go to mods\update\x64\dlcpacks and paste the folder (slick_tintedattachments) there
2. Then you have to go to mods\update\update.rpf\common\data, open up dlclist.xml and add this line: dlcpacks:/slick_tintedattachments/ (together with starting Item and closing Item, like every other entry), be sure the entry is inside the both "Paths", again like vanilla entries
3. Last two steps - you have to go to mods\update\update.rpf\common\data\ai and open weaponcomponents.meta, search for "COMPONENT_AT_SCOPE_MEDIUM" and under <CreateObject value="true" /> add this entry <ApplyWeaponTint value="true" />
4. Do the same for "COMPONENT_AT_AR_AFGRIP", under <CreateObject value="true" /> add this entry <ApplyWeaponTint value="true" />
5. The mod is installed, have fun!