This isn't about the pulley removal, but instead goes to the reason the pulley had to come off.

  I have found that Torx drivers are good for removing stripped allen bolts. The oh-so-common 6mm can be removed with a T-45 bit, driven home (gently) with a hammer. Once the Torx bit is set in the stripped-out allen, it can be taken out just as normal. This requires no better access to the "dead" bolt than usual, and also requires no drilling or use of Easy-Outs. Great!