I don't think you can. I just hooked up an old atari and I just spliced the wire from the atari with an extra cable wire I had laying around. It worked great. But the format of rca input and antenna/cable input is different. You might be able to manage video, but you won't have audio. I recommend just using the cable input. I guess if you want to spend 20 bucks on the modulator you can, I just am a cheap skate and don't fall for buying extra stuff when I can just cut and splice a simple wire. But if you are nervous about that kind of stuff then take the expensive route. I figured sega genesis, not really worth spending an extra 20. If you want to play those games you should try getting a modulator online. They are pretty easy to find and then you'll have like 500 games. You could spend 10 bucks and get a computer gaming paddle to simulate the sega and you'll be set for just 10. I went on a long time here, good luck.
