Hi,
if you can get at least one micro-controller (like an Arduino), it's very simple, you just hate to send en AT frame trough API mode to change the status of you output but with only 2 Xbee I don't really think about it.
Here is a youtube channel that show you basic exemple of Chat between Xbee :
Your text to link here....
And here an official DIGI exemple of "how to do an Xbee switch".
Hope i can help you