It's been a while, but today I installed the latest OpenSim build on Linux, did the necessary configuration stuff, and tried to teleport from Linden's Vaak region to my own OpenSim region. And it worked!
The only problem I have is that my avatar doesn't rezz, and the terrain remains invisible. So all is not yet 100% good, but I'm definitely on my way.
I just teleported from a Linden Labs owned sim to my own and back! How cool is that!