If I want to change VNET_MODE, how do I get this change reflected in eucalyptus.local.conf?

The man page for eucalyptus.local.conf states that it should not be edited directly, and instead that euca_conf should be used to make changes.

I'd like to change the VNET_MODE from MANAGED-NOVLAN to MANAGED. There's already a eucalyptus.local.conf file that looks like:

# network configuration from the input configuration file
VNET_MODE="MANAGED-NOVLAN"

I don't see an obvious euca_conf command for changing this configuration option. I can edit eucalyptus.conf, but it looks like the existing eucalyptus.local.conf configuration will take precedence.