Currently, the default enchantments of custom items must be vanilla enchantments. But, there are some plug-ins that add custom enchantments. It would be nice to make it possible to add default enchantments that have a custom enchantment with a given name.

It looks like Bukkit doesn't provide a proper way to register enchantments, so I don't think there is a nice general solution for this. I will postpone this until someone finds a nice general solution.

Support for Crazy custom enchantments has been added to custom items 11.