Best way is just to wait. It grows fairly slowly --- on rock. It tends to get on the glass---in your case probably acrylic, where it is a pita. My advice assuming a typical nanocube lighting, get some softie coral you happen to like, keep your alk around 8.3 and your magnesium at 1350 (Salifert tests, Kent supplements, real easy) and your prospective fish AND soft coral will be happy. Coralline will hitchhike in on something the softies are attached to, and eventually, with that magnesium level, you'll have as much coralline as you want.