Pokud nevíš, jak tam zabudovat parametry, pak si najdi funkci, která umí i parametry:

function ShellExecAndWait(const FileName, Parameters, dir: string;
  CmdShow: Integer): Boolean;
var
  Sei: TShellExecuteInfo;
begin
  FillChar(Sei, SizeOf(Sei), #0);
  Sei.cbSize := SizeOf(Sei);
  Sei.fMask := SEE_MASK_DOENVSUBST or SEE_MASK_FLAG_NO_UI or SEE_MASK_NOCLOSEPROCESS;
  Sei.lpFile := PChar(FileName);
  Sei.lpParameters := PChar(Parameters);
  Sei.lpdirectory := PChar(dir);
  Sei.nShow := CmdShow;
//  Εδώ έχω ένα πρόβλημα...
  Result := ShellExecuteEx(@Sei);
  if Result then
  begin
    WaitForInputIdle(Sei.hProcess, INFINITE);
    WaitForSingleObject(Sei.hProcess, INFINITE);
    CloseHandle(Sei.hProcess);
  end;
end;