Digital BW, The Print

I've some older FP4 35mm negs that I used expose at 200 asa and develop in Acutol, 
they are pin sharp but much more grainy than the film/developer I use now. I tried to 
reduce the visible grain in a scan by applying the Grain Surgery plugin with Photoshop 
on a freinds Mac, but it was greyed out and wouldn't run. It would run on colour 
scans. Is this typical, does this type of software only work on colour or C41 process 
B&W?

Steve Bell