Here's how to enable or disable the services via serial terminal on the NION.
1. Dust off your propeller beanie, you need to use the vi text editor.
2. Edit /opt/pion/etc/settings/services_conf.xml to look something like this:

3. Don't forget to save changes.
I had to figure this out today on a NION with no frontpanel display. I don't know how useful this is but it might come in handy some day.