Negadoctor is a module in DT and not a plugin. I have an Epson V850 scanner and the software is crap for negatives. It clips the highlights really badly. So I tend to scan the negatives as a positive which gives the orange inverted color output as a 16 bit Tiff file. I then use negadoctor to invert it.
I then use GIMP for most spot and scratch removal as it is much quicker than DT for extensive restoration tasks.