I always thoght they went ON the cuff, so I started doing some searches and this was the only
reliable information I found
General Orders 102 November 25, 1861
III--In time of actual field service, officers of cavalry, artillery, and infantry are permitted to wear the light blue overcoat prescribed for enlisted men of the mounted corps.
From the 1872 Regulations:
Officers serving in the field may dispense with the prescribed insignia of rank on their horse equipments, and may wear overcoats of the same color and shape as those of the enlisted men of their commands, and omit epaulettes, shoulder-knots, or other prominent marks likely to attract the fire of sharpshooters; but all officers must wear the prescribed buttons, strips, and shoulder-straps, to indicate their corps and rank.Clear as mud ain't it? One opion I found said you could wear it anywhere you wanted; on the collar, on the chest, on the cuff, on the chest, ect. BTW I wouldn't go by his opinion.