Summary:  I calibrated MC2 pitch and yaw offsets to spot position in mm. Here's what I did:

1. Changed the MC2 pitch and yaw offset values using  ezca.Ezca().write('IOO-MC2_TRANS_PIT_OFFSET', <pitch offset value> ) and ezca.Ezca().write('IOO-MC2_TRANS_YAW_OFFSET', <yaw offset value> )
2. Waited for ~ 700-800 sec for system to adjust to the assigned values
3. Took snapshots with the 2 GigEs I had installed - zoomed in and zoomed out. (I'll be using these to make a scatter loss map, verify the calibration results, etc)
4. Ran the mcassDecenter script, which can be found in /scripts/ASS/MC. This enters the spot position in mm in the specified text file.

Results:  In the pitch/yaw vs pitch_offset/yaw_offset graph attached,

• intercept_pitch = 6.63 (in mm) ,  slope_pitch = -0.6055 (mm/counts) 
• intercept_yaw = -4.12 (in mm) ,  slope_yaw = 4.958 (mm/counts)