Hi Bob,
It is the Root that decides the radio channel.
As for sample configs every network is different so sample configs dont really work here
You simply need
All Bridges with the same SSID
One Bridge set to Root on this same bridge set the radio channel
the other 2 bridges set to Non root without clients (if you want radio clients to associate to the remote ends like an AP then set it to non root with clients)
After that then the configs are what ever features you want to use like WEP 802.1x/LEAP TKIP MIC etc but these configs will be pretty much the same on all 3.
Here is a link to the configuration guide for the bridge I am sure it will answer your questions
http://www.cisco.com/univercd/cc/td/doc/product/wireless/airo_350/350brdgs/brscg/index.htm