WinAPI SetDllDirectory / GetDllDirectory

procedure TForm1.Button1Click(Sender: TObject);

var

  BL: DWORD;

  BF: PWideChar;

begin

  GetMem(BF, sizeof(255));

  SetDllDirectory(PWideChar('C:\\xxx'));

  GetDllDirectory(BL,BF);

  ShowMessage(WideString(BF));

  FreeMem(BF);

end;