This is pretty cool. Good work so far. Let see if we all can't help you be successful.
There is a great article
here on getting picky angels to eat. The guy who wrote the article has weened some of the most difficult fish (mostly angels) to frozen using this technique. Basically the idea is to make a mush for foods and then freeze it onto whatever the fish normally eats. For instance he froze it onto empty clam shells; naturally, the fish would pick at it and start to eat. As the frozen food thawed, it would start to float into the water column and eventually they'd get used to eating right out of the water column during normal feeding time. I used the same trick to get my Potter's Wrasse to start eating and now have the fat bastard fully trained onto frozen. There is a famous collector in China who uses the same technique to acclimate all of his rare angels (like the $1000+ kind).
I wonder if you could try the same trick with bare/dead acropora skeletons until they get used to frozen?