i don't seem to have enough hands to coordinate pumping out fluid, pouring in new as fast as it pumps out, and keeping an eye on everything at once.

i suppose you could start and stop the engine, or shift in/out of neutral to turn the pump on/off. this would give you a chance to catch up.

 

Be better to have an extra person there to assist.

 

That's the hot ticket. Get all of your ATF bottles open, outlet line in the bucket, etc. then have the helper start the engine, and shift into Neutral if the unit isn't sporting a modified manual valve. Then it's just a matter of pouring until the color changes and hollering at the helper to shut it down when it's time.