Yes, that custom attribute is left over from me trying to rememeber how to get it to work.
As for figuring out DC's - it was a painful experience. I recall lots of nagging the development team for better docs. They have a pretty good website now that puts together the possible methods and examples of each method in action. In the Component Attributes window, just click on the functions tab. Then look for the little "more" url link. It brings up this page:
http://sketchup.google.com/support/bin/answer.py?hl=en&answer=108144
And I recommend starting just like you are. Play around with onclicks and hidden variables, then move on to rotation and moving and copies, etc. And good luck!
Chris