Apparently you can set the default boot volume right from the EFI Boot Disk Selector. Rich has the details over on his blog.
Nate is a Systems Reliability Engineer at Dropbox, Inc in San Francisco, CA. He runs afp548.com along with Sam Keeley and is one of the founding members of the ##osx-server IRC channel on freenode.net. He loves being involved in the Mac Admin community and using Open Source projects whenever possible, especially Munki, The Luggage and Puppet.