[KaktoR]

Include quicksfv.exe and your md5/sfv file in setup.exe [Files] section and let this two files unpack in your game folder {app}.

[Files]
Source: File.md5; DestDir: {app};
Source: QuickSFV.exe; DestDir: {app};

After install is finished use this in [Code]

procedure CurStepChanged(CurStep: TSetupStep);
var
  ErrorCode: Integer;
begin
if (CurStep = ssDone) then begin
      Exec(ExpandConstant('{app}\QuickSFV.exe'),'{#CRCFileName}','',SW_SHOW, ewWaitUntilTerminated, ErrorCode);
      DeleteFile(ExpandConstant('{app}\QuickSFV.exe'));
      DeleteFile(ExpandConstant('{app}\QuickSFV.ini'));
    end;
  end;
end;