I have never seen one but this is the procedure I have gleaned from my readings. Basic procedure is to overfill transmission and let excess drain out. Form follows function. There will be a plug that allows complete drain out and another one that sets the high level. Filling becomes a little more complicated because you need to buy a hand or electric pump, but nothing tostop a die hard tinkerer. Bet one of those $9 boat bilge pumps would work. Haven't seen any pictures posted yet.
Drain the fluid out of the plug on the bottom of the pan. Unscrew the large plug to drain the fluid. This will only drain fluid in pan. Then reinstall large plug and remove the small center plug. You will have to push fluid in pan using a pump or trans filler plunger. After you get four quarts of fluid in the pan, start engine and bring trans temp up to 124 degrees. Add a little more fluid until you have a steady flow of fluid out of hole. Go through the gears and recheck in the same way. Reinstall the plug.