thought i'd stop lurkin for answers and help out a little. found these products on google.
http://www.clearmask.com/headlight_v2.htm
http://www.clear-guard.com/productsearch.asp
i checked clearmask.com, they seem to have a kit for the s14, zenki and kouki. you can probably find more results if you type "clear headlight film" on google. i'm sure there's a way to get the film in bulk to make a custom kit, in case you can't find it specifically for your car, like for s15 headlights. clear-guard.com has the film in bulk. anyways, hope i helped a little.