If the compass is spinning this is because the Mag is not currently used and you moved the board while gyro are initializing.
For physical orientation, compare the onboard Mag from Revo and The Auxmag, referring to the small dot on package.
Or simply use the bars to find the correct orientation.
The Roll value can be easily found because based on Z axis reading and how is facing the chip (up or down)
Next try Yaw orientation using 90° steps, assuming the Auxmag chip orientation is orientated something 90° from board point of view.
When all bargraphs remains/still to 0, the orientation is correct.
Like the help text says, this assumes both Mag are calibrated and without error.