Super Sculpey gets a bit softer with sculpey III added. I think most folks add the III to get a more opaque material. translucency of super sculpey will hide all the mistakes and make it really hard to finalize a sculpey piece.
I find it really hard to get detail in sculpey with what I've done...I think if I use it again I'll be using it to rough something out only..
Sculpey III does make Super Sculpey softer, however if you're looking for a temporary solution, I use that canned air that is used to clean computer parts. If you turn it upside down, it'll spray out condensed air which will freeze the sculpey for a few minutes so you can get in and do small details.
This isn't a permenant solution, and I'm not sure that it's good for the clay if you use it a bunch. It might lead to more cracking when you bake.