1) You know the stage coordinate system CStageW in World coordinates -> Thus X,Y,Z (the origine) and the rotation angles A,B,C (or similar, which give the orientation of the system). Right?
2) You know the camera coordinate system CCamW in World coordinates. You know them, because the camera is fixed on the robot arm, and you know the position and the orientation of the arm. Right?
3) With a homogenous coordination transformation, you can translate a point from one to another coordinate system. It consists of applying a rotation and a translation. http://en.wikipedia.org/wiki/Rotation_matrix
explains how the rotation matrix is calculated by using the Euler angles. For Kuka robots, the geometric operator represents this transformation.
-> With CStageW you can calculate the matrix TStage that will transform the coordinates of a point given in the stage coordinate system into world coordinates.
-> With CCamW you can calculate the matrix TCam that will transform the coordinates of a point given in camera coordinate system into world coordinates.
4) If you want to express a point given in stage coordinates Ps into camera coordinates Pc, you have to calculate
Pc=Inv(TCam) TStage Ps.
Inv is here the inversed matrix (which is in this special case also the transposed matrix).
5) with the formula from 3), you can use the matrix M=Inv(TCam) TCam to get the rotation angles between the 2 coordinate systems.
Hope this helps,