Followed the details from a forum post – went very smoothly. You will need 12qts of ATF fluid to do a complete flush.

Basically the process is

1. Drain from the plug
2. Drop the pan
3. Drop the filter
4. Install new filter
5. Reinstall pan with new gasket
6. Add about 4qts through the dipstick tube
7. Disconnect the transmission fluid return line, attach hose to it
8. Start the car, pump out a quart, add a quart
9. Repeat until only new fluid is left.

Random pics below!