IME they don't require direct feedings if you have fish in the tank (and you're already feeding the fish).
That said, if you want to target feed them, you could try blowing some thawed frozen cyclopeeze or (chopped) mysis onto them with a turkey baster. You could try other finely chopped meaty seafoods as well.
Personally I don't bother target feeding Euphyllia sp. anymore as growth rate and health seem to be fine with or without the target feedings (again, with fish in the tank that are being fed daily). Just be sure to maintain normal Ca and Alk levels.