I don't agree here. I have flushed many a cooling system with nothing more than a garden hose. I dare say hundreds. Pull the stat, run the motor with the radiator drain open along with the upper radiator hose off, put the garden hose in the fill of the radiator, and pump all the crap out. This is the way we did it at the garages I worked at during college as well and I was taught this method by several different master mechanics. I have never, personally, seen or heard of this causing any problem.
But, I am in no way a professional mechanic.