Thanks for the feedback Fred and Handa. Maybe you are right. There is no need to reinvent the wheel.

I just wanted to think a way to make the ATF change more effectively (and also safely) as it is expensive and a hassle removing the plastic cover to do the ATF. Maybe it can be stretched to 40-50k using this technique.

I bought the car a month ago at 130k km and the ATF has not been changed. Its lucky that the transmission is still good (smooth) as the previous owner uses the car mainly highway driving and uses it gently (I dont think he ever engaged the vtec). I replaced the oil with redline D4 oil as redline was the oil I used on my previous car and it was good. I bought it for approx $85 per gallon (3.7 L), its expensive.
To me doing the flush is a little more risky but I am sure it is more effective than conducting multiple drain and refill as the drain and refill method mixes the old and new oil before the consecutive changes. The number 2.5 L I used is a number I used to ensure that no (significant) air get into the system (we have 3L inside the pan). This can be reduced to 2L being more conservative. Fred the reason for not filling the dipstick as the system is flushed is done so that full attention (reduce the risk) can be given to the volume of oil that has been removed to the drain pan and alert the driver to stop the engine.

Fred, can you please tell me if you notice some difference between Redline D4 and Valvoline maxlife ATF fluid?