The vacuum assist line will disperse the seafoam to all your cylinders on your car, but for future reference, seafoam does have a spray style specifically for use in the intake system:
SeaFoam Spray
I've personally seen it becoming a normal stocking item at all the local parts store here in MN. And if something is commonplace in the midwest, it should be stocked elsewhere with regularity.
I have always had a pressurized spray bottle that I used to dispense the Seafoam in the past, but now with the new style spray will no longer need to do that.
Hope this info helps out
It is also a good idea to get a small rag wet with seafoam and to wipe off any buildup on the throttle body plate and surrounding ares in the intake manifold if you use the vacuum line method with the seafoam. That way you get all the gunk out of the intake manifold.