I was just checking the Haynes manual... sounds messy if you're completely 'flushing' the system. Draining the system and re-filling is no big deal: unscrew the plug underneath, let the fluid draing and then refill. That's it. To flush the system, they're talking about draining the system, undoing the thermostat, hooking up a garden hose and then pushing water through. I've never done it, I need to do it as well, I want to try to do it myself since the local guys will want to charge me an arm and a leg for it.
to make it simpler to fill it, they sell this thing at advance auto for filling tranny fluid, works perfectly, just ask them and i'm sure they'll know what you're talking about, and was only like 3 bucks and some change if i'm not mistaken. Went there to get something to use when i was doing my clutch swap and came across it, one of the best investments i've made.
And just fyi, just in case, fill hole is on the front side of the tranny, not at the top, as most people would think it is, and drain plug is at the bottom just in front of where the dogbone mount comes across? forgotten already[
] . you'll need an 7 or 8mm torx/allan to get it, you'll need a bit of leverage on it to break it loose. What i did was use a wrench and put the circular end over the torx to get the leverage i needed