GTAIV Patch 6 + Patch 7 only: trainer.asi, trainer.ini, scripthook.dll into the GTAIV main directory (c:\program files\rockstar games\grand theft auto IV on X86 windows versions, or c:\program files (x86)\rockstar games\grand theft auto iv on X64 windows).
GTAIV version lower then patch 6: trainer.asi, trainer.ini, scripthook.dll - OLD Patches into the GTAIV main directory (c:\program files\rockstar games\grand theft auto IV on X86 windows versions, or c:\program files (x86)\rockstar games\grand theft auto iv on X64 windows). Rename Scripthook.dll – OLD Patches to scripthook.dll.
GTAIV + TLAD as DLC: trainer.asi, trainer.ini, trainertlad.asi, trainertlad.ini, scripthook.dll into the GTAIV main directory (c:\program files\rockstar games\grand theft auto IV on X86 windows versions, or c:\program files (x86)\rockstar games\grand theft auto iv on X64 windows).
GTAIV + TBOGT as DLC: trainer.asi, trainer.ini, trainertbogt.asi, trainertbogt.ini, scripthook.dll into the GTAIV main directory (c:\program files\rockstar games\grand theft auto IV on X86 windows versions, or c:\program files (x86)\rockstar games\grand theft auto iv on X64 windows).
GTAIV + TLAD + TBOGT as DLC: trainer.asi, trainer.ini, trainertlad.asi, trainertlad.ini, trainertbogt.asi, trainertbogt.ini, scripthook.dll into the GTAIV main directory (c:\program files\rockstar games\grand theft auto IV on X86 windows versions, or c:\program files (x86)\rockstar games\grand theft auto iv on X64 windows).
EFLC only: trainertlad.asi, trainertlad.ini, trainertbogt.asi, trainertbogt.ini, scripthook.dll in the EFLC main directory (c:\program files\rockstar games\EFLC on X86 windows versions, or c:\program files (x86)\rockstar games\EFLC on X64 windows).
GTAIV and EFLC: trainer.asi, trainer.ini, scripthook.dll into the GTAIV main directory (c:\program files\rockstar games\grand theft auto IV on X86 windows versions, or c:\program files (x86)\rockstar games\grand theft auto iv on X64 windows). AND trainertlad.asi, trainertlad.ini, trainertbogt.asi, trainertbogt.ini, scripthook.dll in the EFLC main directory (c:\program files\rockstar games\EFLC on X86 windows versions, or c:\program files (x86)\rockstar games\EFLC on X64 windows). Of course if IV is lower then patch 6, use the scripthook.dll – OLD Patches and rename to scripthook.dll