If, by "work like a Will", you mean let you do something like this:
Opponent: has Ancestral Recall in their graveyard
Me: play Shaman's Trance, pay U to cast their Ancestral Recall
I'm pretty sure that wouldn't work, because you couldn't cast the AR if it were in your graveyard either (again, unless you had another card that let you cast spells in your graveyard, like casting your own Will, or Regrowth/Eternal Witness/Nostalgic Dreams, or whatever). Is that what you meant?
yea, I thought that...and now feel 10 points dumber. Blah, can close thread, no need to waste any more room. Thanks