I see that my modification interests you. Here's the basic info I used to modify my tg-16 for component video:
http://www.gamesx.com/rgbadd/duorgb.phpOnce you have soldered the wires onto the huc6260 chip, you can either feed them directly into a homemade or commercial encoder internally and install rca jacks onto your system, or feed them to a port, in my case i used a 8 pin din, and them put them through an encoder such as a jrok:
http://www.jrok.com/hardware/RGBv4/index.htmlThough the problem with the jrok and tg-16 is that the red is slightly overdriven, so the colors won't be 100% correct.
One other thing to note, you may want to use a lm1881n for the composite sync line, they are cheap enough and can alleviate problems with syncing sometimes:
http://www.gamesx.com/misctech/lm1881.htmHope this helps, if you have any more questions let me know!