If this is a 3.4l engine - the usual method is to install a socket with a breaker bar resting against the frame, and then simply hit the starter very briefly.
This worked nicely on my '98 4Runner to break this nut loose. This is a well documented and frequently used method. Just be careful that the breaker bar doesn't fling into something that matters in the engine compartment. You might get an assistant to help, and be sure to disable the ignition so that the engine does not start.
If you want to use the trans. to hold the crankshaft, put it in 5th gear and chock the wheels.
Colo Springs, CO