Respectfully Request methods of collecting the flush. The water table is very close where I live and I don't want put that stuff into the ground. -thank you!
Jack said vehicle up in the air, pull the wheels, and slide a very large tub/pan under it. Flush to your hearts content.
Rani, if you can't or don't want to tear down the motor to hot tank it (understandable if it runs great). The next best thing would be to remove the exhaust, starter and accessories, punch out the freeze plugs and blast the coolant passages with a pressure washer (or a garden hose with a concentrated stream on the nozzle if you don't have a pressure washer). It's also handy to have some scrapers and such to worm into the passages to dislodged the heavy sludge.
Install new freeze plugs, and run some flush through the system to get the whatever may have settled to the bottom of the block.