1.) Take the outflow hose off the transmission, and put a 10-foot extension on it... route that extension up and over the passenger door mirror so that gravity keeps the fluid in the hose instead of running out)... drop the open end of that hose in a 5-gallon bucket, and duct tape it to the side of the bucket so it doesn't jump out and douse your driveway.
2.) Take another 5-gallon bucket and drill/tap/TRV a bung into the bottom of it
3.) Connect another 10-foot extension hose to that bung, and place the bucket on the hood (on a towel if you have nice paint). Duct tape it down, too, for the same reasons stated above.
4.) Connect the other end of this extension hose to where the inflow hose connects to the transmission.
5.) Use a tube-clamp or a set of vice grips to clamp off the extension hose near the bucket.
6.) Fill the bucket with tranny fluid (Walmart has it in 1-gallon containers for cheap)... you want to use at least one-and-a-half times what the owners manual specs for your transmission to account for what's in the hoses. Me, I'd just drop the dime and put in two-and-a-half times the specced quantity to insure a thorough flush.
7.) Remove the pinch clamp or vise grips (this will start a slow gravity-cycle of the fluid), then start the vehicle, and cycle it through its gears. Keep an eye on the bucket fluid level and shut the vehicle off when you run out of feed fluid.
8.) Disconnect and drain the extension lines and quickly reattach the factory cooler lines -- any fluid you lose while doing this can be topped off shortly.
9.) Restart the vehicle, run it through its gears again, then top off the tranny fluid through the filler or dipstick.
10.) Cap off the 5 gallon bucket of used fluid and take it to a recycle depot.
11.) Wipe out the inside of the feed bucket, throw some paper towels in the bottom, then label and bag all the extension lines, clamps, etc. that you used, and put them in the bucket, too. Cap off this bucket and put in in the garage for the next time you want to do this task.
12.) Post here and tell us how easy it was, and how much you saved...

NOTES:
Clear tube will help you see when you're out of fluid in the feed bucket... and will also help you see the change in old fluid and new fluid.
This will change out MOST of your fluid, but not all -- I'd guess 90%. See my previous message for ways to keep the fluid clean in the first place...