You can do it the individual plantlets way, I have done this in the past, I'm sure a few other people on here can back me up it takes AGES. Some people like Amano for example recommend planting a few at a time but a good method I found with my potted glosso was to just take the base rock wool out of the pot. Cut off the bottom so you have the plant at the top and about 1cm thickness of rock wool under the plant, then you cut this into cm squares and bury each square in the substrate a few cms apart, this seems to carpet very quickly providing your parameters are right.