The ROS package uses SmartServo and the motion command reads "motion.getRuntime().setDestination(jp);"
jp being the joint positions we publish via ROS on the topic iiwa/command/JointPosition
(sorry if thats a bit vague, I'm not to familar with smart servo and the java application wasn't written by me as it came with the ROS package)
Oddly I can get smooth motion by scaling up the mouse output/increasing the variable I define.
However this isnt really a solution as this also scales up noise from the mouse, meaning we can't be as accurate as we would like.
Also I'm technically telling the robot to go to unsafe postions, not really an option in our line of work.