TellstickDuo is now added to NetHomeServer. The new Home Item "Tellstick" is available in the nightly build. I have tested it on Windows 7, Ubuntu and Raspian (Raspberry Pi). I guess it will work for MAC as well, but I have not been able to test that yet. For transmission, all NetHome protocols are supported as the NetHome encoders are used. For reception only protocols supported by both Tellstick and NetHome works, as the Tellstick does the decoding of received signals in firmware and does not expose the raw pulses for the NetHome decoders to work with.
What took the most time was surprisingly to get good driver installations for Windows and Linux that works with Java, but I have compiled driver packages together with installation instructions for Windows and for Linux.