I've had no problem in the past by using an old accessory belt.
With the belt only going around the pulley and the alt., there is a lot of slack left over, the slack is then jammed into the pulley, held in place with a screwdriver, preventing the pulley from turning.
Opposite for tightening.
Although this is not the "official" method, it does the job.
It also ruins the belt for future use.

DM&FS

At 10:28 AM 1/16/2012, Jim Felder wrote:
>This is for John Rogers, not me, thank goodness. He has a leaking rear
>seal. I have removed this bolt with the crankshaft in a big vise, but not
>in the car. Bentley calls for a special tool for obvious reasons. Has
>anyone R&R this bolt without special tools or removing the engine?
>
>Thanks,
>
>Jim