This person had to run Matlab from the PC, so he had to use Dynamixel SDK directly, and there is a way to access the CM-550 directly via UART or USB port. It involves the use of the Dynamixel concept at a more advanced level:
If you can describe what you want to do, I can retarget my suggestions more to your needs at a high system level, because I have never used ROS or MATLAB!