#46645
Place the "dsound.dll", "scripthook.dll", "firstperson.asi", "firstperson.ini" and lastly the "systemtimesync.asi" files into your root GTA IV folder, the one which has the exe's "LaunchGTAIV.exe" and "GTAIV.exe".
For steam users this is in: "..\steam\steamapps\common\grand theft auto iv\GTAIV\
For retail users this is in: "..\Rockstar\GTAIV\" I believe.