I have a Turbo duo that has been S-Video modded on ebay if you want to look at it. If you want to have your own system modded I am not so sure. I don't think member D-Lite does it anymore(multimods.com). You also have the option of getting an RGB-modded system as well. With RGB, you can convert it to component video using a RGB-YUV transcoder. Those can be had for $60 on ebay nowadays. That's how I have done it and I love playing Level 5' in Dracula X in glorious component video! Hope I've helped you out a bit.
Erik