Here is a video I found of someone doing the partial change on a 2009 Infiniti G37 Coupe. Seems pretty straightforward.
The dealer near me initially agreed to do entire fluid exchange, then chickened out and did a partial change. I'm not confident that they even did that correctly, but it shifts and drives well and the temp is ok.
I will be doing this myself too as soon as my Quick Jack lift gets here.
https://www.youtube.com/watch?v=8lE3lZEcaqY