When originally looking into wireless bootloading using XBee, I found this article on the Ladyada site extremely useful. Here are the steps you need to configure for Firewing. It assumes you are using the X-CTU configuration software, connected to a Sparkfun Explorer Board. Please note that an equivalent host board should work just as well.

Pan ID

This should be a four digit hexadecimal number. Both the transmitter and receiver must have matching IDs

Interface Data Rate

The Firewing XBee loader uses a baudrate of 38400

Packetization Timeout

This value is taken directly from the Ladyada site and works very well with the Firewing loader. It basically determines the timeout value between transmission characters.

D3 Input / Output Pin

This pin is connected to the Firewing XBee software reset circuit, so needs to be configured as an output.

Output Enable

Again this value is taken directly from the Ladyada site and works well. It prevents data appearing on the serial line and just toggles the data pin (D3IO)

Input Address

A value of FFFF will match all XBee moule input addresses.

Don't forget to press the X-CTU "Write" button after making all of the changes!