I used to have a 1660 Photo.
As I recall, you need a couple of things:
Either the 1650 has to be a 1650
PHOTO model or, if a "plain" 1650, an unobtanium accessory backlight that attaches to the cover.
A film / slide holder - not absolutely necessary for all-manual scanning but it's really hard to keep a strip of film centered and straight without it.
AFAIK, there is no auto-scan software / driver
for those units that will do what you want. The scanner has limited external control so locating, defining edges, balancing different exposures from frame to frame etc. is not possible.
TWO caveats:
1. I'm not 100% certain there's no such software BUT I DO do know there is NO automated Epson Scan version and I was never able to find any other app that would do that either.
2. That all said, my 1660 (which probably had the exact same engine as the 1650) was a damn good unit in its day. It was amazing with transparencies and even a 35mm color neg straight to TIFF was pretty slick - as long as you didn't get greedy and try to print larger than say, 4 x 5.
My CD doesn't have the operating manual on it (Epson genius) but they are all still online even now.
https://epson.com/Support/Scanners/Perfection-Series/Epson-Perfection-1650/s/SPT_B11B146021#manuals