I'm now working on this fairly seriously. To start off I had to create a patch to flumotion-0.2.2 to make it build, and then write the ebuild to apply it. Those two come from the bug at
http://bugs.gentoo.org/show_bug.cgi?id=138214
The best way to get started is probably to start the worker / manager / admin by hand rather than with the init script, in the foregound on three separate terminals, so you can see what is going on. I currently have a gstreamer problem with muxers, which tells me to file a bug report, but not much else to include in it.
In theory you shouldn't have to hack about with the planet.xml file. If you do you can load / save copies using the Import / Export commands on the Connection menu in flumotion-admin. I think the options tie up with the gstreamer ones, i.e. try gst-inspect on the gstreamer components concerned.