Yes, we've done this for DH, (low sodium). On embarkation, we went to the spot where you can meet with the Maitre'D, and they had us choose from a couple of options available that evening. That evening our waiter brought DH the dinner menu for tomorrow and let him order from a much wider selection, because when they know in advance how many special meals they need, they can create enough 'batches'. He was also able to pre-order for Sea Day Brunch, or any breakfast in MDR the night before. It worked out well.
ETA: He as able to order even the soup as low-sodium. We tested it because I ordered the regular version that night, and we could really tell the difference between the two minestrone versions.