@L29Ah actually, i gueess it is not possible now.. but you can remove a package with "emerge -av --depclean PACKAGENAME" the -v option tells you, which package you should remove before.. it is a hard way, but somehow possible, if it is not a system-package whick is needed ;)
@L29Ah Цепочку из команд представить себе могу, а вот чтобы одной - хз.