cqc.cs is a mod where you can do special combos with fist, bat, knife etc
should give you some kill moves that look cool with the mod
install in grand theft auto iv/scripts (you need asi loader and scripthook)

put w_knife.wdr and wtd in weapons.img with sparkiv or openiv
(thanks to ac.amir, coulnt send you a private message, i cant for some reason :(

and the main thing, put melee.ivaud in pc/audio/sfx/resident.rpf and replace with
sparkiv or openiv