sorry i misread your post thinking you already had slide film ...
you could always make a black and white print inter positive, then a contact print of THAT for your negative.
a bunch of years ago i was asked by a guy in a bluegrass band to make copies of a print his friend made
for him and his bandmates ... the person who took the photograph lost the negatives or something, and she was AOK with it
so i contact printed the positive print onto rc paper, and got a negative, then i just did the same thing with the negative
over and over again to get the positive print. as long as you don't have the brand name on the back of the paper it comes out OK
if there is a brand name, well you get a watermark
ortholitho works wonders too ! ( and no watermark )
have fun !