Thanks for the instructions! I have a lot to learn about bridged networking, and my problem doing this shows it.
I have followed the instructions on the wiki, creating an ifcfg-peth0 and changing ifcfg-etho to the specified content. When I restart the network, I get
Device peth0 does not seem to be present, delaying initialization. [FAILED]
followed by
Device eth0 already exists; can't create bridge with the same name [FAILED]
Any suggestions about how I've failed to do this properly?