Sorry can't help you as of yet I've not needed to remove my one. I did also look on other sites re the M62 & one site there is a guy called Subby who's got a highly modified R170 and it looks like he changed the S/c pulley when the S/c was out of the car, while porting it. But I don't see any need to do that just to change the pulley.
Hopefully, somebody will be along that's already done it. Stay tuned.