I think that once a cap's crimped on, it's only a destructive method like pliars or scissors that's going to get it off. You can decant into atomisers without removing the spray mechanism either by spraying straight into it (using little squirts so it more dribbles than sprays) or by spraying via a small stainless steel funnel. There's also the Travalo atomiser, which fills from the tube you get when you pop the spray head/nozzle off. That's not a cheap option if you have more than a few to do though.
Do a google search for 'perfume decanting' and you should get some more info up.