Helped a friend with this problem on his Civic. Chocked both sides of the wheels, he stood on the brakes, and I jumped up and down on the 3/4" breaker bar* with a 4' steel pipe on the end. I really had to reef on it to get it break loose, I swear I thought the nut would strip or the threaded section break off.
*not your average breaker bar: It's a "T-Handle Socket Breaker Bar"; The head is a solid piece of tool steel with a hole drilled through it, and a 3/4" solid rod as the bar, through the hole. There's no articulation joint or ratcheting action to break. The risk of using The Negotiator is that the bolt/nut snaps off. I don't foresee the circumstances on the 4Runner where the Negotiator loses; there's no fasteners that are big enough to break it. I always think carefully before I bring it out to negotiate a problem as that the results can be worse than the stuck bolt.
A very important aspect of such a tool is using it properly. To get maximum leverage, the mounting must be as short as possible, keeping the bar as close to the bolt as you can. So you'll need a 3/4" socket that fits perfectly, preferably a shorty socket. The further the bar is from the nut, the more leverage it'll have to bend the fastener, rather than rotate it... thus increasing the force required to remove, or encouraging to strip the fastener's shoulders off. It goes without saying to use a 6pt socket on a 6pt fastener, of course.
As others have said, a shop with a heavy duty impact could zip it off for you. Then just retorque it to spec to drive home to do what you need to do.
