I don't have a photo handy, but I had a large (36mm?) impact socket sitting on the shelf that I'd bought when I rebuilt my transmission (which I never ended up using).
I took a new ball joint nut and lined up the socket against it, and used a magic marker to mark the 4 notches from the nut onto the socket. Then I pulled out the angle grinder and cut away everything on the socket except four tabs to line up with the notches.
This method is only cost effective if you already have a spare socket - I remember paying about $40 for it originally.
Others have used a 4wd wheel bearing tool as in this thread:
http://forums.pelicanparts.com/porsche-911-technical-forum/199565-front-suspension-refreshening-3.html
.... these don't seem to be available in Oz, so I went the DIY route. Mine looks similar to that tool, without the wall on the outside of the 'tabs' (and not so neat).
HTH -
Al