Although pondini has instructions in the C12 troubleshooting to load 5.6 utility.. I discovered a free utility to do it.
Is very easy.
How to load 5.6 into ML.
1. Download 5.6 for Lion.
Click to open the dmg but do not attempt to install the pkg.. it won't work anyway.
2. Download and install unpkg.
Run unpkg on the desktop.. it is very simple.. drag the AirPortUtility56.pkg file over to unpkg.. and it will create a new directory of the same name on the desktop.. drill down.. applications utilities .. there lo and behold is Airport utility 5.6 .. drag it to your main utilities directory or just run it from current location.
You cannot uninstall 6.1 so don't try.. and you cannot or should not run them both at the same time.. so just ignore the toyland version.. the plastic hammer.. and start using 5.6.. a real tool
Archive is a very poor way to backup.. just so you realise it is very slow.. it backs up the entire TC internal drive.. and the TC drive is blocked for the whole time.. it cannot walk and chew gum at the same time. Next time you want to do it.. it will backup the entire disk again.. no incremental .. no rsync. .no useful way to use it as an automated backup of data. TC shows its primary function as destination for TM and any other use Apple themselves seem to be promoting is extraordinarily unwise.
Posting here does little or no god. By all means, send your feedback to Apple at http://www.apple.com/feedback/timemachine.html
To me, a more important omission is the button to "Disconnect all users."