You want to use seaform on a vacuum source that is post throttle body (to insure adaquate vacuum). Typically, you can remove the brake booster line from the brake booster, plug the hole with your thumb while the vehicle is running. Then, crack your thumb off of the ID of the hose and pour in the seafoam. Don't worry about spilling it, you wont (due to the excessive air velocity, the seafoam will get sucked in and not spill).

 

Ill have to look in to doing this. I pulled off the hose from my PCV valve, and it doesnt look too bad but it is covered in oil. Good news is its all clean oil in a thin layer on the sides, and not sludgy (The previous owner actually changed it)