How can I separate colors by layer in Illustrator?

I did a three-color Live Trace, and output the colors to swatches. Now I’d like to assign each of these three (spot) colors to their own layer. I’m sure this is super easy, and I’m just over-looking something, but I could find no obvious command, nor could I drag the swatches to the layers palette. Some googling brought me to this site, although not to an answer. How do I do this? Thanks!