Wii component cables are few and far between these days, and the ones you do actually find typically come with an eBay tax of $150 or more. So, with that in mind, the DIY community has taken to task making their own. Their exploits are documented in the link dump below. Enjoy, and report back if you get creative.
Tutorial by tkamen
http://www.tdficq.com/wii_component_cableAnother good tutorial without pictures (worth reading both before you start).
http://www.avsforum.com/avs-vb/showthread.php?t=755734NFG/GameSX Wiki Pinout Page
http://nfggames.com/wiki/doku.php?id=av:wii_multi_av_pinoutHelpful threads if your cable doesn’t work
http://nfggames.com/forum/index.php?showtopic=2387
http://nfggames.com/forum/index.php?showtopic=2363&st=0&#
[Thanks, Lee]