Installation:

Use MP Clothes and paste the files to mpclothes\dlc.rpf\x64\models\cdimages\mpclothes_male.rpf\mp_m_freemode_01_mp_m_clothes_01
Optionally you can rename the number so it's in different slot
This will add the nails to the decal/decl slot

Obviously you can also replace vanilla files in any of the dlcs, or rename the models and textures, but the one above is optimal way.