-Lay down some towels in case of spilling
-Turkey baster out the reservoir
-Fill Reservoir with fresh fluid
-Push through using the pedal starting with the farthest wheel, checking the reservoir level often until it's clean/clear fluid.

I try not to push the pedal all the way to the floor on old cars or ones with dirty fluid.

I run DOT4 in everything, usually ATE SL.6 for ABS/ESC vehicles or ATE TYP. 200 for non-ABS vehicles.

I'm willing to bet the dealers typically don't flush fluid whatsoever, there's nothing about it in most owners manuals.