If its just to get the pulley off have a look at jaspers comments on how to get this bolt undone (6th post) in
viewtopic.php?f=1&t=7299 this post. Thats the way I'll be doing it.
If you go down the angle Iron route then its a "tool tip" in the haines manual, so not sure of the exact size pop the cover off, and have a spy. Those teeth are hardened, so if it comes to a battle between the starter motor, and the starter ring, the motor will always loose.
The car in gear is also recommended by haines.
I'm all for getting the right tool for the job, but if theres a simple solution, like 2 8mm bolts or drills to lock the engine for the timing belt then I'd rather have a bash that way.