My one size fits all solution to every problem; it has never failed me yet.

But, yeah, I dunno, really; I would probably just chunk his scattered crap back in his room (or the street) whenever he abandoned it and make him deal with it, or at least get it out of the rest of the house, but beyond that, not sure what to tell ya. If you cannot yet move and your parents are not ready to intervene themselves there is not much you can do, particularly not if he can run complaining to mom and dad every time you try to lay down the law. As long as you are living with your folks (which is the impression I have, perhaps wrongly, from your comments) they have the authority. You cannot make them use it and trying could just make the situation worse if they see you as overstepping yourself, while your brother can just ignore (or further provoke) you since he knows you are in no position to do anything but keep getting impotently mad.

I assume in all this that you have already attempted the "sit down and discuss the matter dispassionately like reasonable adults" route. If a strongly antagonistic dynamic was already present that was probably a hopeless task from the outset because he was predisposed to hear his annoying judgemental sister rather than an objective human being. Good luck with it; hope things get better sooner rather than later. Ibuprofen gel caps FTW.