The Hagan frenched headlight kit is made for steel fenders and welding is required. you could use this kit and attach it with fiberglass resin, but its not recomended. If you want to french your headlights in fiberglass fenders you will need to make a fiberglass headlight bucket and attach it to the fender using fiberglass cloth/matt and resin. Making a bucket is reletivly simple, make a male mold for the female part, in this case a large plastic cup coated in a few layers of dried carnuba wax would work fine. After you wax the cup or male mold just layer it with a few layers of cloth or matt and resin, let cure and it should pell off of the mold with little problem if you wax coted it. The wax acts as a demolding tool. I would first look at the many different fiberglass body manufacturers to see if they off a frenching kit that you could adapt to your fenders.