It doesn't exactly work that way... you don't configure anything in the SX-200 for the Voicemail PMS interface, other than to turn it on in VM options if you have the correct licensing. The exact details of how to configure the system AND the iPocket are in the Technician's Handbook.
Remember to integrate fully with a PMS system, you need TWO iPockets and TWO serial connections to the PMS server, one for the Voicemail interface and one for the PBX interface, each one configures just a little differently, but the details are spelled out in the tech handbook for both.