How to install designer plugin in Qt Creator 2.8 for OSX?

[Northern L. I. <in...@no...>]

Anyone figure out what the correct procedure is for getting the designer
plugin working in Qt Creator 2.8 on OSX?  I have it working in the
standalone Designer (because that looks for external dylibs and frameworks
in a different way).

I tried use the published procedures without success.  For one thing, there
is no "designer" sub-directory in the app package.  I created that directory
and put the dylib in there but Qt Creator say that it's not a valid plugin.