I figured this out when messing about with writing something in Dmajor, which is not a scale I use often, but was inspired to use since I want to get better at using scales-with-sharps, and it's my girlfriend's favourite scale.
To go from CM to Cm, perform the following sequence: CM, AbM, Fm, Cm.
( BPM)
CSS required: load abcjs-audio.css
To go from Cm to CM, perform the following sequence using the flat7: Cm, BbM, FM, CM.
( BPM)
CSS required: load abcjs-audio.css
Generally, use the flat6 or flat7 chord for modulation!
Alternative modulation from Cm to CM using flat6 (Ab):