I've had them for a few weeks, but last Thursday I was seriously procrastinating about cleaning the house, so I decided to give it a shot. I started with grape, and dyed a couple of them purple.
First, I got them really wet and decided how I wanted to color them. The one on the left is a square, and I twisted and rubber banded it in tie-dye fashion. The one on the right is oblong and I just left loose.
Next, I sprinkled the Kool-Aid powder over the top of both scarves and squished it around until I got the level of color I wanted. Then I stuck them each in a Ziploc bag and mostly sealed it, leaving a corner open to let the steam out. I microwaved each one for two minutes, then took them out and left them in the bag to cool.
Once they were cool, I took them out of the bags, removed the rubber band from the square one, and rinsed. Not a drop of color came out - the heat completely sealed them. Finally, I hung them up to dry. The next morning, there they were, just waiting for Caitlyn to play with!
Oh, and one word of warning - if you try this, wear gloves. Otherwise you, too, may wind up with grape-flavored hands! :-)