Our Wireless Serial App only does radio communication between two Wixels, but another forum member was able to modify it so you could change the radio channel on one of the Wixels using a USB command (effectively allowing it to select which Wixel it is communicating with). You can see his post about it here. By the way, if you all want to do is control the I/O lines on the receiving Wixels, you might try looking at the I/O Repeater App for an example of how to go about doing that.
Brandon