Hi, I'm trying to implement a server similar to one of those that is used to configure Airport Extreme or Time Capsule devices over Airport Utility.
The problem is I don't have any of such devices and network communication protocol is not public so I wrote a little program that records network messages between Airport utility and Time Capsule or Airport Extreme.
I would appreciate it if you record and send me messages for analyze.

Instruction.
The program can be found here.
Requirements.
  1. java >=1.6
  2. MDNSResponder (for Windows users only) I believe it is already installed as a part of Airport utility. Anyway you need dnssd.jar to be present in your system.


Startup
Change password in your device.
From the folder with the program run in terminal:
for OS X users
Code:
java -jar apbsRecorder-1.0.jar
for Windows users
Code:
java -cp <Path to dnssd.jar file> -jar apbsRecorder-1.0.jar
The program searches for devices in the local network. If it find any it will show device as a button. When you click the device button program turns to record mode.

In record mode

Start Airport Utility and choose "Configure Other..." item from File menu.
Enter ip address showed in the bottom of my program's window. Password is the same as in a real device.
If all is OK, program will record all messages from airport utility and device.

Do some setting modifications (change name, DHCP, wireless, enter wrong password, etc.), but remember all actions will be sent as is to the real device. I need as many records as you can make.
I don't think it works with not configured devices, but if you you try to record messages from new device or after full reset it would be great.

When you finish please send me content of log and records folders to e-mail.
Thank you.