Dear Michael,
Sorry for the delay. We have not tried PiLLoW ourselves with SICStus 3.7 because we have not installed 3.7 until very recently.
We plan to make the mods to PiLLoW for 3.7 in the coming days. However, in the meantime, perhaps someone in the list has done it already and can send the patches?
Cheers,
Daniel Cabeza