I use the Evothings 1.20 for this project instead of the 2.00 betas for now. So get the Evothings 1.2.
I wanted to use the HTML5 built-in ColorWheel, but unfortunately it isn't consistant across browsers. It is fantastic on Firefox, but lame on iPod (virtually non-existant) and minimal on Nexus. So instead use the HTML5 Canvas to display a custom PNG image. Then just read the color of the pixel at the coordinate where you click. This way you can use whatever picture you want as your color chooser.
I am still working on the project. But you can easily look at the index.html and ColorWheel.js file with any regular browsers page source reader.