My MM Ren Amarone's raisins were a golden color. Maybe you could go to a nice health food store and buy some fresh, organic golden raisins and add them in.
I'd wash them first, as they might be coated with something (sulfites, sugar). Might think about what preservatives they could have in them, though. That's why I would try to get organic.
As I wrote about last week, I sure wish a person could buy just grape packs by themselves.
Maybe some of you who have your own vineyards and wineries might think about packaging grape skins and selling them, if the legal and logistical hassles are not a show-stopper.