Hello and welcome to Pearl/Just answer.com, Super mechanic here. I will do my best to help you with your question. My goal is to help save you money and I hope you will be completely satisfied with my answer. If you need any more on it just let me know.
About your vehicle.
There is a heavy duty cooant system flush made by "Dupont" that we use for very dirty system, (some clogged radiators) which has acid in it and it comes with a nuetralizer that you have to run through the system after the cleaning. Called, "Dupont Heavy Duty Cooling System Flush".
You could use a flush machine but in the event that you don't have one, (which most of us don't) then you could use a "Tee" in a heater hose, but I have found that sometimes causes more problems, (with leaking, or clearence) and it would be best to let it run out the upper hose, (at radiator end) while filling the radiator with clean water.
Then after nuetralizing you can fill the cooling system in the normal way.
Standard Coolant Filling Procedure
Special Coolant Fill Procedure