Automatic fluid exchange

[Solid T D]

I've been going through all the forum notes, and tried the YW service manual, but for the life of me, I simply cannot find the info I'm looking for.
I started an Auto Systems and Auto Technician class at a local occupational center. I've been noticing that my tranny is taking a bit longer to switch gears than it used to. I understand this is normal, but, I wanted to change the tranny oil, just as a precaution, as I am fairly rough on my Yaris.

I know that this Yaris uses ATF-WS(Toyota only ). My question is how much ATF do I need to buy, and do I need special tools/machines to do this?

When I asked, at the parts desk, the gentleman said the tranny needs to be pressurized when changing the fluids. So, I took it that changing the fluids needs a special machine.

Please hit me with your collective knowledge and wisdom oh wise ones!