BACKUP YOUR ORIGINAL FILES!
Before replacing, make sure to make a backup folder and throw your standard dlc there.
Installation:
1.Open OpenIV,
2. Deagle update\x64\dlcpacks\mpapartment/models/cdimages/weapons.rpf
2.1. Sound update\x64\dlcpacks\mpapartment/audio/sfx/dlc_apartment
3.Drag everething from downloaded archive and put it in this folder.
4.Enjoy!.
Credits:
Litrium