Randy I've done it a couple times. I recommend putting it in the START_UP in \mas90\HOME for it to persist. Add a line in the 200 block where the other PARAMs are:
SET_PARAM 'MB'=1800,'VE'
Starting with 4.40, Sage uses 1800 (1.8 GB) for the segment size and they set the related VE param as well. I followed suit when I set it for older versions.