with all my scanners, I use the holder that is correct for the film type. too many issues trying to use the wrong film in the wrong holder. I use the fh-8355 holder for 35mm
but if thats all you have, I would guess you would have to scan the strip with the 120 holder, then either reduce you scan size to go frame by frame, or scan the whole strip and cut the individual frames in a photoshop style program.