As far as the program, there must be a function in the menus that you aren't seeing that's causing the DICE to function. You did say its on color negative which CAN take advantage of Digital ICE so perhaps it's automatically on for that setting....
I found the PDF instructions.
But you are right there isn't much for options.
My only other suggestion is to scan as a transparency and invert the image from negative to positive in post.
I've heard viewscan is great, I have Silverfast but I can't figure it out honestly it's a terribly non-intuitive program, so I've gone back to the supplied Epson scan program which seems to work much easier, so I hope viewscan isn't as complicated as Silverfast...
Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk