Sending commands on Xbee Zigbee over-the-air

I have Xbee Zigbee S2 2mW. I can enable security AES-128 key by configuring it through X-CTU. My question is can the key be set automatically over-the-air by sending commands from my laptop, so that I do not need to use X-CTU?? Moreover is there any chance when I have a mesh network of lets say 5 nodes, to automatically cooperate and change the AES key periodically?

It's in the documentation. Do a Google search for "Xbee trust center".