Sigh. ICeCoffEE has a showstopping bug. Strangely enough, I never ran into it earlier. Somehow, in some applications (Address Book is the only one that comes with the Mac OS I've been able to find) the input manager loads late enough that some NSTextView classes already exist, and not only does the posing not take effect on them, they stop working properly (refusing to become key). This means I may have to implement it with libPatch instead of as an input manager, in order to get in early enough.
The installer was coming along well, but I'm going to put off working on it, or ICeCoffEE, until the end of the week. Too much real work to do.