IIRC it used to be impossible to display it in a split, it required a separate frame (that is, windowmanager-level window).

There were some dirty hacks to fix that, but led to more problems with window & buffer switch ordering (and layouts for things like ediff)

May all be fixed now, this was years ago when I last played with it, but haven't really found the need for it, instead of ibuffer-mode, ido-everywhere, and smex. (Probably helm too if I can ever be bothered to set it up properly)