Followed the directions in http://www.panticz.de/Intel-AMT-vPro-under-Linux, to enable direct VNC access (IP KVM like). Everything worked well while a monitor was physically connected.
However, once the monitor was no longer connected, Linux disabled all display output, and VNC only showed a black screen. Took some time to find the right kernel command line parameter to force output:
Note the "e", which force enables the output.