uh, not quite. what you want to do is use your toe for BRAKING and work the throttle with your heel. not the other way around. proper procedure for a heel/toe downshift is this:
toe (i use the ball of my foot, not just the toe) on brake, apply pressure
depress clutch
move shifter to lower gear
blip throttle using heel
let clutch back out
the purpose of doing this is to rev-match all of your downshifts. its easier on the driveline, and it helps keep the rear wheels from kicking out suddenly. of course, all of the above takes place in about one second or less. it just takes practice. once you learn how, you'll wonder how you drove without doing it.