Writing a VPN Installer/Configurator

I’m in the process of writing an installer for my newly-configured VPN. In the past, we’d had a Cisco setup (which I just had a script call the installer, which threw in the right payload, and was done), but we’re now on a standard L2TP connection. I know the system writes the info to /Library/Preferences/SystemConfiguration/preferences.plist, but every entry is preceded by a UUID. Is there a defaults write command that could insert a new VPN connection? Thanks in advance.

Model: Xserve
Browser: Safari 530.19
Operating System: Mac OS X (10.5)