Warning. Always make sure you backup the files you are modding before you decide to mod them. In this case, you need to make a copy of playerped.rpf which you can find in:
C:\Program Files\Rockstar Games\Grand Theft Auto IV\pc\models\cdimages

Installation:

Open the playerped.rpf file with OpenIV or SparkIV and import the .wtd files i provided and overwrite the original. Click rebuild and then Save it. Launch the game, and the clothes should either be in the russian shop or in niko's wardrobe.