Well this would be a negitive that you would use in an enlarger to make prints. I would think you would need a positive for a projector. I have never seen sheet slides I could not read by holding them up to a light. I think the projector would show the negitive as a negitive on the screen? Even 35mm Slides are in the positive when showen in a slide projector.
I myself have tried making negatives on a printer, I have taken the Photo Editor from MS and told it to change the photo to a negitive and print it out on transparency. I then put it in an enlarger and made prints from it. I have not made any Bromoils from them yet. Before I printed them out I made the photo the size of a med-format negative so it would fit in the enlarger. I would think you could make it as small as a 35mm negative but you would have to cut the transparency down before you print them not to waste the rest of the transparency.
later Sir William