I have heard some LDS members say that the act of resurrection is actually a Priesthood ordinance. Is there scripture or words from LDS leaders stating such? Or is this an assumption?
Brigham Young spoke of it as a Priesthood ordinance:
It is supposed by this people that we have all the ordinances in our possession for life and salvation, and exaltation, and that we are administering in these ordinances. This is not the case. We are in possession of all the ordinances that can be administered in the flesh; but there are other ordinances and administrations that must be administered beyond this world. I know you would ask what they are. I will mention one.
We have not, neither can we receive here, the ordinance and the keys of the resurrection. They will be given to those who have passed off this stage of action and have received their bodies again, as many have already done and many more will. They will be ordained, by those who hold the keys of the resurrection, to go forth and resurrect the Saints, just as we receive the ordinance of baptism, then the keys of authority to baptize others for the remission of their sins. This is one of the ordinances we can not receive here, and there are many more.
-- Journal of Discourses, 15:137-38
While Latter-Day Saints do not hold the Journal of Discourses to be authoritative scripture, this is the word of a prophet on the matter, and President Spencer W. Kimball considered this talk authoritative enough to quote and comment upon in General Conference.