How to make mozilla run headless

[gaze]

I've been combing through the Jaxer source code for a while now trying
to nail down the bare requirements for making mozilla run without any
sort of user interface or actual rendering engine. Any pointers
towards how to do this on a fresh copy of the mozilla source code? I
noticed that gecko has an embedding API for which you can specify UI
controls, events, etc, but Jaxer doesn't seem to hook into these.

Thanks!
Evan