No anger, just frustration that these things are 1) difficult to explain and 2) even when I do, somehow it still looks like my fault.
I'll try again though: as stated in the FAQ, Samsung does this for their own apps, built into the firmware -- which is very, very, very different from offering (documenting) this capability for third party apps.
Now, as it happens, someone did figure it out, even though it's undocumented and not intended for third party apps.
I just tried it out, and it worked fine on my three Samsung devices (Note 3, Galaxy S4, Galaxy S4 Mini). This will be included in the next development build (in a couple of days).
Screenshot: standard TouchWiz launcher on a Galaxy S4 mini. This is the actual AquaMail launcher icon, not a widget.
Supposedly, this is also possible on Sony devices (although the code is of course entirely different). I'll try it if I'm able to borrow my nephew's Sony Xperia P.