Hi bis48,
there are few threads about this technique from the past:
viewtopic.php?f=6&t=1501&hilit=water+soluble+paperviewtopic.php?f=6&t=2395&hilit=water+soluble+paperI would recommend testing it first, to get a hang of it. To day, the biggest challenge (for me) was to get pictures in without getting them to float, or have any air bubbles. Because those will look bad.
Make sure you take your water soluble paper to a local Kinko's or Office Max shop, and ask them to print it fro you on their laser Xerox (Fiery) printer. Colors come out bright and vivid, but most importantly, those colors won't run in your soap.
I also was using SLS-free base (with BB carries), and found that the yellowish cast is just too much. I am not sure what type of clear base you use, but I would recommend getting something ultra clear for embedding photos and pictures.