I've had the pleasure of replacing those gaskets in my 09 G37. The symptoms you describe are exactly what I had. My 09 G had the paper gaskets which is why they blew. I'm guess that when they upped the displacement to 3.7 from 3.5, no one thought to upgraded those gaskets. Only after a few years of this issue did they upgrade them. The new ones were reinforced with metal. Back then, G owners used to use a magnet to make sure they bought the redesigned gaskets.
I put over 100k on my G with the new gaskets and no issues. Luckily my M is a 2012 so it shouldn't be an issue, "shouldn't" being the operatives word. But if it happens again, I'd like to think I'm well prepared.
The motors are identically so the procedure will be the same with the exception of removing all the components to get to the timing cover itself although that shouldn't vary too much either. Check out myg37.com there is a ton of info on this exact issue. If you've ever changed a timing belt then this is a walk in the park although it is extremely time consuming. If you're doing it yourself, give it the better part of the whole day.
Interesting note: back when I did this, infiniti dealers did NOT sell these gaskets themselves but instead the entire back timing belt cover which is 100% pointless and a lot more work to replace. Not to mention much more expensive. Nissan does sell just the gaskets. I looked up a 2009 370z on autotrader and took down the vin. Gave it to a nissan dealer and got the gaskets that way. It's the exact same motor so it all works. I ended up changing the timing belt tensioners, guides and water pumps while I was in there. I left the chain and had no issues when I sold the car with 190k miles (gaskets blew out at around 90k)
Hit me up if you need some additional info. Sucks to see this happen even in the M