I'm pretty sure that you just use the factory mounts and add the pocket underneath the cd player in that install. Metra makes that pocket. I have usually used the direct bolt in method for this install. This is why.
Last year my car, and about 7 other cars, were broken into in my apartment parking lot here at Purdue. I walked around and looked at all of the kits that were used and how the thieves removed the decks from the dash. All of them had the plastic kits that were easily bypassed/broken. I used the factory (metal) brackets that are bolted into the dash in my car, instead of using the plastic kit. My car is the only car that retained its cd player. I have marks on my dash where they tried to pry it out... but no such luck.

One thing about using the factory metal brackets though, which some installers and users love and some people do not love. This is that the cd deck is only flush with the dash when the detachable faceplate is removed. This is good when thieves look in because they think that there is just a blank or that somebody took the detachable faceplate with them. It is a good deterrent, but some thieves will break in and look for your faceplate if they have time.In Nissan/Infiniti installs, I recommend this method. Just remember that you need the pocket underneath if you dont want to see the inside of your dash.Good Luck!