The project settings for "make" allow specifying that "make install" is ran as root. It also allows picking three different tools to elevate the privileges: kdesu, kdesudo and sudo. (at least on my system those three) Those are fixed options in a listbox in the settings. But on my system I don't have kdesu, I only have a kdesu5 executable. And I see no way to make use of that (short of creating a symlink for it). The config files also just seem to save the option selected (1/2/3) so seems no direct manipulation of the executable filename there either.

It would be nice if that listbox in the project settings allows entering a custom string.