Configuring the router is pretty simple. I have a fancypants real router that does all my internal home connection, and so I just use this one as a bridge.
Configure the SSID as "Free Public WiFi". Disable DHCP, let the main router hand those out. Make sure to disable wireless admin access and also setup firewall rules on Main Router to prevent these clients from getting into the internal network.
Did you know: if you do happen to have one of these routers (MR814v2), you can actually flash the v3 firmware to it? This will enable WPA-TKIP. Read more here: