The pulley you are referring to is the power steering pump pulley and yes you need to unattached the power steering pump from the engine. This is done by removing two bolts behind the pulley. There are three large holes in the power steering pulley and these holes will allow you to gain access to the two power steering bolts. One bolt is located at the top right of the power steering pump and the second bolt is located at the bottom left. Once these bolts are removed the power steering pump will drop down and pivot towards the firewall. DO NOT DISCONNECT THE POWER STEERING HOSES. This is not necessary since the power steering pump is not being replaced. This will give you the clearance you need to access the bolts without obstructions.
For the removal of the Serpent belt you will need to remove ONE engine mount bolt. The motor mount bracket is attached to the engine in three points. The engine mount itself sits on top of the frame. Standing over the passenger side fender and looking into the engine compartment you will see the attachment points for the motor mount. The bolt on the bottom right side of the motor mount must be removed. You will need an E8 torx socket for this (it is a stud bolt with a nut, since this is an older car, the nut may be rusted to stud, so the stud may come out by placing a socket on the nut...so an E8 socket may not be required). Once the bolt is pulled away from the motor remove the spacer between the motor mount and the engine which will allow the Serpent belt to be removed. DO NOT REMOVE OR LOOSEN ANY OTHER MOTOR MOUNT BOLTS. This is not necessary. If you remove or loosen any other motor mount bolts you will need to support the engine.