seafoam is very thin and will probably run right past the piston rings, but it is a very good solvent so you cant go wrong there. honestly as long as you keep enough in there to keep the top of the piston covered then you'll be fine, doesnt matter if its MMO of seafoam, though MMO is cheaper ($3.88/32oz at walmart. i'd do 1-2oz in each hole and check periodically because it will leak past.
i just did an MMO soak in my dads honda because it was burning oil, about 1-2oz in each hole, after 6 hours, 3 of the cylinders were dry, and one actually retained the MMO (which is slightly thicker than seafoam) now only time will tell if it stops burning oil because the rings freed up.
when it comes time to start it, crank it over for about 10 seconds before putting the plugs back in, its very easy to hydrolock an engine when you are pouring that way it can blow out any excess fluid. ideally you would want to let all of the fluid in there (seafoam/mmo) work its way past the rings and then start it that way you avoid taking the chance of hydrolocking it.
if you use seafoam though i would recommend changing the oil shortly afterwards due to it being a straight solvent, where as MMO actually has some lubricating properties and can be run in the oil for quite some time, and is great for cleaning out engines.
good luck!