You're not using the 5ed rulebook are you? That kind of spell was not in my book, at least.
If this spell is, however, usable, then why not just use CrTe(Me) or some other elemental form to give the "servant" the body right from the start? Using Im in a situation like that one seems kind of useless to me.
Where did the Calebais Hrools come from? I haven't read the book but I sincerely doubt that the divine has granted life/human-like consciousness to weaselmen.
If you look at the CrIm spell in the 5th ed core book, your see the spell that has gone mostly unnoticed. Using a formulaic spell, you created a ghost servent with limited indenpendant intellect at the cost of a +6 mag Memtem requisite.