Please note: The latest PowerCore software offers 64-bit driver support but contains 32-bit plug-in binaries only.
Start Logic 9 in 32-bit mode (Select the Logic icon in the applications folder and press either Apple+i or right-click 'Show Information'). In the Information window, check the "Open in 32-bit mode" checkmark). It will then scan any new 32-bit AUs.
Once this is done (and assuming the AU passed validation) it may then be accessed with the 32-bit Audio Unit Bridge running Logic 9 in 64-bit mode.