I just did it with a 1/2" breaker bar and a 6 point 19mm socket. What I did was to place a piece of plywood in front of my radiator then I wedged a block in between the plywood and the breaker bar to hold that socket on the bolt tight.
Breaker bar was on top of the driver side frame.
Bumped the starter and she broke loose.

I think the key is to use a 6 point socket, wedge it in there and have as little slack as possible ... so that when you hit the starter it has full direct contact with the bolt and can do it's trick.

I tried it earlier with a 3/8" breaker bar and it broke the axis pin of the breaker bar immediately.

Good luck with yours, hope ya get it without too much more grief.