how to configure network via command line?


Can someone help me with the following problem.

I need to setup a new Internet Configuration (PPP) in OSX without user interaction.

There are several command line utilities that seem to be able to do the job, but none of them has good documentation.
These are niutil and scutil.

Anyone knows how to make a change in the Preferences.xml file (where you can change the Network prefs).
When this file is altered, the settings are not updated until a reboot. I think I have to restart configd and/or lookupd with some special command to reread the pref file.
How can I do this (kill doesn't seem to do the job)

Please help!