Those rear spark plugs can be nasty to get to. However, they can be accessed with the upper intake plenum still installed. For more information of this tip, visit ETCG's video: http://www.youtube.com/watch?v=0IcfeyA3L3E
I cannot say if this will work on other 1mz-fe Toyota cars. This is just a generalized tip for Camry, Solara, Avalon, ES300, and Sienna cars/vans that use 3 coils, not the earlier 6 coil design.
How To Change 1mz-Fe Rear Spark Plugs