1. Extract Pariah.awc from the .rar archive.
2. Click on Edit Mode, then drag and drop the .awc file in this directory:

GTAV / Mods / update / x64 /dlcpacks /mpchristmas2017 / dlc.rpf / x64 / audio / sfx / dlc_christmas2017

Feel free to comment about any issues you come across. The sound is not an add-on yet so further editing of the volume and other parameters is not yet implemented.