Freeman is right. I have done it. I did have a good write up of the procedure posted but it got lost in one of the forum conversions. (PCV HELL) I had 70k miles when I replaced mine and there was no problem with it.
If you decide to tackle it... (my advise is not to) You can reach it from underneath. You have to reach about arms length up into the engine with the front wheels on ramps. You can get about 1/16 turn of a wrench at a time. You will need some LONG (like 10") bent needle nose and straight needle nose pliars to get the little hose off and on. It is best to replace the little molded hose when you change it because you will probably tear it getting it off. It is about $18 at your local nissan dealer for this little sucker.
Nissan wanted $300 to change it! (They wanted to take the intake manifold off!)
Takes alot of patience.
Hope this was helpful. (or scared you)
-Matt