Hi There

using a unsharp mask with 35 mm is totally ok, just be very careful with dust and all the rules apply that would be in effect for larger film.

Donald Miller has a lot of great threads , posts and an article on unsharp masking and I am sure he would be of great help if you run into any snags. I have not done masking for a few years and since I am not actively masking film I think my advice would be from memory, but he is actually presently doing this.
have fun