Peter,
Does yours have the color module? If so, just dial it in -- I can send you a scan of a filter chart for the V35 that shows what filtration to use for the Ilford contrast grades.
Otherwise, you can always buy the acetate filters and just lay them on TOP of the negative or get the Ilford/Kodak under-the-lens filter kits and use them.
Otherwise, I've used the plastic filters under the lens without any problem -- just be sure to focus through the filter and not insert them after focusing for max sharpness.