Lock arbitrary joints when solving IK using tracIK

Hi guys, I am using the trac-ik Plugin in MoveIt! to do my IK calculations. Is there any way to lock certain joints, i.e. make the solver behave as if that joint would already be in it's limit? I guess I could implement a workaround that temporarily sets the corresponding joint limit to the current joint position, but is there a cleaner way? Thanks in advance, Tim