timing belts on "distributorless" engines

when changing timing belts on Taco's with distributorless engines or engines with the coils over the plugs , when you change timing belts or chains , you know how you have to re-set the timing? well , my question is do you have to reset the timing and if so how? or does the ECM do it for you automatically? If you remeber on the old engines with distributors, you simply loosened the distributor and rotated it around to get the right timing. Anyone know or did it?