A white or bright colored fine tip paint marker would work best. I would also give the record a light couple of sprays with clear plastic spray paint to preserve the signatures when the wedding is over.
By
08/07/2010
What a neat idea.
By
08/04/2010
You could maybe use a gold or silver paint pen. They make some with glitter too. Sharpie pens come in a wide variety of colors, tho I would do a "test signing" on another record to see which is the best.