never run the transmission dry
its pritty easy to do but i suggest you get approx 10L or more of fluid before starting
remove the trans hose off radaitor (after the radiator/cooler) meaning the cooler will be flushed also.
you will need to pump the fluid in as soon as the key is turned on, and i do suggest you get someone on the key.
ok once your all set up with the hose off and in a big bucket, one you dont want to use again get your 2nd persion to hit the key.
the fliud will now be flowing and you should be adding fluid all the time at this point.
also keep an eye on the draining fluid, once you see the fluid change from a brown burnt color to the color of the new stuff thats when your helper shoud key off and stop pumping fluid in.
connect up all hoses again and check your level, adjust as nessesery. if its too full than remove the hose again and crank but not start motor. reconect and check level again.
--------- DONT MISS THIS STEP-----------------
once your happy, go for a spin. come back and check the level again. and your set
and about the tranny cooler idea, yes verry good idea, mount it all up after doing the flush and dont use old coolers (there cheep $110 or so for a kit)