The same way we did it all the years of the Cold War, with an enemy just as insidious. There is NO NEED for the "Patriot Act"--just the removal of the LIMITATIONS on intelligence activities passed after Vietnam by the anti-war Democrats, and especially those imposed by the administration of Billy Jeff the traitor.
"Where do you live? Maybe we can be sure that Al Queda knows how well proctected you think you will be without some of the Patriot Act provisions."
I live across Puget Sound from Tacoma--feel free to notify any Al Quaeda members you know.
Many forget also it was a Republican POTUS of that era's bad judgement which brought us the sudden rise in terrorist attacks. Take a bow Gerald R Ford for sparing the lives of foreign heads of state who support terrorism and a prohibition upon killing them for doing such.
Many of the terrorist investigations in the 1990s failed to become more fruitful and meaningful because of the legal limitations in warrants and intelligence sharing, some limitations due to changes in technology, some due to the nature of what is being investigated, potential acts of war, as opposed to already committed acts of "crime". A crime that has already been committed does not have the time sensitive nature in its investigation that a potential terrorist act does. Some of the provisions recognize this difference and the demands of it.