you have to download openiv (or sparkiv) to insert this into your game
https://openiv.com/
you have to go to GTAIV\pc\models\cdimages in your gta 4 directory and open playerped.rpf
remember to enable edit mode and then right click
hand_diff_000_a_whi
and
hand_000_r.wdr
click replace on them
and then replace it with the file in the modpack
thanks - oborlex