The neat way to do it is with the prestone flush kit, the one with the T fitting in the heater line. I initially drain it with one of those squeeze type kerosene hand pumps then stick some water in there, put the kits hose diverter in the neck with 5 feet of hose on the end into a 5 gallon bucket from our cat litter containers or laundry detergent containers, I save them up
Then I back flush the system into the containers till it runs clear, I've never filled up more than two of them. From that point on it's water, then I put the 7 hour flush in and drive it for a day or more, reflush, drain and refill. Thats how I used to do it, now I just take it to my friends shop, hookup the sun machine and suck out ALL the coolant, take the machine off, refill with water and 7 hour flush.
I suppose if I was going to come up with something I'd make an adapter to fit in the upper radiator hose on the radiator end, a reducer of some sort and put a garden hose on the end to a bucket, start the engine and let the coolant pump out as soon as the tstat opens while adding new water to the radiator, letting the water pump do the work. But since I have access to the sun machines I never followed thru on it.
