"If you want this to work, you need to re-proritize". You need only stand up to your manager and in a calm clear manner explain why this will ultimately come back to haunt them

This also gives you an opportunity to 'refactor' the extent to which FeatureX is really *important* (as opposed to just fluff) ... unless you work for the type who says "I don't care how much it takes, just get it done" ... but that's a whole different realm of dysfunctionalia.

BTW ++ on this whole thread and especially the funniest node I've seen all year.. stvn++

(note: not to make light of folks who work for *whatever* kind of site ... )