I have used the method described by Bluesugar except for the part about homemade finger pepperoni.
I drained the entire thing and flushed with a garden hose attached via a T-fitting on the heater hose line. I also disconnected the upper and lower radiator hoses at times, plugged them with my hand, let pressure build up some, and then let the water power dump. I then filled with water and added the white vinegar. I ran it for a bit to circulate through the system, let it sit for an hour or so, then did the power flush/dump again to get all the vinegar out (well, dilluted down to effectively nothing). It helped get the scuzz out. Refilled with distilled water and antifreeze, and called it good.
The brown sludge shows up eventually, so I consider this just a maintenance item to put on my list of periodic crap to do.