Epoxy works for me. Secure the coral so that the growing edge will encrust onto an adjacent rock surface. With plating Montipora its generally easier to attach them to a slight incline so that as they grow out they will encrust over the rock face. If you put them on a flat surface they tend to plate outwards and may not grow over the rock that they are sitting on.
Securing Propagated Corals by Anthony Calfo
http://reefkeeping.com/issues/2002-1...ture/index.php