I see it another way. Its true that both effects have to apply in the order you wish but no matters what you do it will ends under your deck.
I mean, if you choose to sacrifice first, then the second effect applies anyway (where is the card at this moment do not change anything) so you'll have to take it from your discard and put it under your deck.
Now if you choose to put it under your deck first, the second effect applies but as the unit is already ''dead'' and under the deck it will not be moved to your discard as it is no more sacrificed (you cannot sacrifice a unit that is not in play).
The FAQ have something about this...