I have been opening them up with a dremel tool and wiping down with denatured alcohol them applying with a toothpick or small brush. After it hardens block it down with 400 grit or so then buff if desired. Again I am no expert and just started playing with gelcoat. But I am happy with he results so far.
Found this today
http://www.boatus.com/boattech/casey/02.htm
And This
http://community.webshots.com/album/107841735XmwxIb