Hi,
Welcome to the forum. We typically ask newcomers to post a picture or two and to include your location in your registration information. You can also add a signature line where it is helpful for you to give us the year and model of your car. That way we can help you better. If you look at this response, you will know I own a 1973.5 911T and live in Oregon.
To answer your question, check out Daniel Sterns Web Site:
http://www.danielsternlighting.com/. He has a tech section that describes a method.