Well, I went poking about and came up empty-handed on pig skin oil soap and also on pig skin oil. I did, however, get lots of hits on the oil/liniment that Steve mentioned in his post. lol
Next, I looked on a few lard rendering sites and ran into one or two folks who tried to render backfat from a pig/hog (which oftentimes still has some of the skin attached), and they complained that their rendered fat never solidified, not even when in the fridge. The advice they got in return was 1) either they didn't render it properly, or 2) maybe the fat they used was from a hog that was raised more naturally (the quality or density of the rendered fat can differ depending on diet).
Where did you say you saw the soap?
IrishLass