I've done just what you're trying to do, and it's easy. Be SURE to use unsweetened Kool-Aid. Put some water in a Pyrex dish and add the Lemon flavor (I think it's Lemonade these days), until you get a nice yellow. Add a touch of Green (Lime), and a smidge of orange (hardly any) to get a yellow-olive. Then nuke for 3 minutes on high. Don't add too much orange, just enough to dirty it up a bit. If you don't see the color you want in the dish, start over. You'll need at least two packs of each color, so you can play around. You can get a nice Harrop PMD colored grizzly hackle if that's what you're shooting for.
Eric