The differential gain starts out at around 20db at 10Hz and goes down to around 16db at 100kHz, so to get CMRR we'd have to manually divide.
Alternately, set up two exactly the same circuits like the one we have now, and use one for the differential gain and one for the CM gain, then divide in the waveform function setup V(v1)/V(v2). This would be possible but you'd have to copy the ENTIRE circuit with ALL elements to do this, then set one circuit to have inputs 1v and 1v, and the other to have 1v and 0v for example, then divide the outputs. That would provide a graph of CMRR vs frequency right in the simulator.
Sounds like fun huh?