Reading RSSI value between 4 x XBees using an Arduino Nano with IO shield

I am trying to create a network that reads the RSSI values between 4 XBees using Arduino Nanos with IO shields - Arduino Nano IO shield - ITEAD Wiki.

However, I am very much a newbie. Is this possible? I can't work out how to connect everything to get this working, as I am not sure where the RSSI output (pin 6) is on the shield. This is the schematic for the shield.

Is this at all feasible? Thanks in advance for responses.