Two options:
#1) Remove the PS pump assembly and set it up in an arbor or hydraulic press. Block the pulley with some steel straps, etc., and press on the pump shaft with a brass rod. That should push the pulley off (or more correctly, the pump off the pulley).
#2) Take a die grinder and slowly, carefully cut the pulley off the hub, then (even more carefully) score the hub, and split it off the pump shaft. Of course, you'll need a new pulley standing by. Someone on here will sell you one pretty reasonably. It's much more preferable to cut the pulley than the pump.
Anyone else with ideas?...
JD