They go on the valve/cam cover were the hose runs from the valve/cam cover to the intake. The purpose of the factory hose is to ventilate the crankcase gasses back into the intake to burn again. You put this lil filter there on the valve/cam cover and plug the intake. That way the crankcase is still ventilating and you're not suckin in hot air into the intake. You want the coolest air as possible to enter your engine.
Here's a pic of my engine. You can see it on the right side of the cam cover, right above the ignition wires.



:EDIT:
LMAO! I just noticed that this was the Honda/Acura section LOL! No big deal, it's all the same!