To get skeletal tracking up and running on Xcode with ofxOSC go here:

http://pkmital.com/home/2011/01/24/streaming-motion-capture-data-from-the-kinect-using-osc-on-mac-osx/

For the problems you are going to have with the libUSB driver look here:

http://discussions.apple.com/thread.jspa?messageID=12438610

If you are curious about arduino robotic arm inverse kinematics look here:

http://www.circuitsathome.com/mcu/robotic-arm-inverse-kinematics-on-arduino