yes you can do a humu trigger with a cuc. but it takes some effort to find get one. it all starts with finding a less aggressive trigger at your lfs. there a few things you will be looking for:
1)you want a trigger fish that is not kept alone, a trigger that is kept alone generaly means it is a very aggressive individual.
2)look for a trigger that when it interacts with its tank mates it is not showing sings of aggression. you want to spend the better part of a hour watching the trigger, observing its behavior.
3)if the trigger shows sings of being aggressive around its home, you dont want that fish. its ok if it is chasing the fish away every now and then but nothing over the top.
this is not a sure way to get a reef safe trigger but it is to get a nice trigger, but it does gives you a better chance for a reef safe.
i trained my trigger to be reef safe and if you get a humu trigger i recomend you do the same. start off with some hermit crabs and feed your trigger A LOT. the trigger fish will eventualy get used to being fed for food and not having the need to hunt. so once the trigger starts leaving the hermits alone you start building up your cuc. eventualy you will have a full cuc. but it takes time to tame a preditor like a humu trigger so slowly buld up your cuc. start with hermits and star fish, then add large snails, crabs, shrimp, then small snails. when you buy a cuc member start of with one. see how the trigger reacts to it then after that if things go well you can get get more of that species.