Here is a link that covers the procedure for the 02-03 Maximas (with
the 3.5VQ).  Your fronts are the same and the rears are easier.

http://greghome.com/Greg's%20Garage/2002MaxSE/SparkPlugReplacement.htm

For your case, 1. there is no engine cover to remove :), 2. the rears
can be accessed directly - you don't have to move the plenum out of the
way.

Off the top of my head.
0. Disconnect negative battery terminal

FRONTS:
1. Remove the Nissan plastic plate over the front valve cover - uses
hex head bolts.
2. Now you'll see the 3 coil packs and harness connectors.
3. Undo harnesses and undo each coil pack (2 screws) and pull coilpack
firmly upwards - they'll pop out - plugs are under there - replace like
any other plugs.

REAR:
1. There is no cover over the coil packs, but if you look between the
passages of the plenum towards the firewall you'll see 3 more
connectors to the rear coil packs.
2. Undo those connectors and undo each coil pack (2 screws).  IIRC the
rear right coil pack (when facing the car) has a bracket in the way
that you'll have to undo first...guides the throttle table or something
of that sort.
3. Be careful undoing the rear coilpack screws - easy to drop :)

Good luck! If you decide to do the plugs at the same time, stick with
the NGK platinums (OEM) - you can get those from Courtesy Nissan as
well.

Nirav