In anticipation of my new pattern, Julia's Lace, (a fabulous scarf), I've created this little bitty video tutorial of the Cable Cast-On. Have fun learning and let me know if you have any questions.
The Cable Cast-On is great for casting-on at the beginning of a piece, enabling you to maintain a pattern motif, choose your own length, and retain shape. The edge is firm, yet elastic, with a great look. It is quite difficult to actually be sloppy with this technique. Ruth, over at Knitting on Impulse, has a very detailed explanation of the advantages, look, and disadvantages of this cast-on.