Unless the MS3 had something radically different than other cars' coolant systems, I would just say do the following. Buy a few gallons of deionized water. Jack the car up and put on stands. Find out where your drain plug is on the radiator (there's usually a little plastic opening you can open so you don't have to take the bumper off or anything). Unscrew and let it drain (takes a while). Once it's done, screw plug back in. Fill radiator with deionized water. Run car for a minute at most. Repeat the flushing process. Do this until you see only water coming out. Then, flush one more time and repeat process with coolant until you see only coolant coming out. This is how I would do mine. There's a bunch of other ways as I'm sure many other people will post on here.