j7 is right. from looking at the files of the mod, I'd say it's impossible to have just one
of the additional endigs by just installing some
of the files.
the best you could get that way is 'braking' the unwanted ending in not installing their scripts, so if you'd chose their dialogue-option, the game would crash (or maybe, if you're lucky, nothing happens at all).
but in order to not have the according dialogue-options, you'd have to edit the mod's dlg-files, as naturally the options of the cut ending and the ones of the fanmade endings are in the same file.
On a personal note, I can't really see the problem you have with installing the full mod and simply selecting the options to get your wanted cut ending. Nobody forces you to chose the other options