I began by creating a drawing in my sketchbook and then scanning it as a greyscale image. In Photoshop I converted the greyscale to a bitmap image (you may need to fiddle with contrast settings while the art is in greyscale) -- see art below left.

I then imported the bitmap file into Freehand (Illustrator and Photoshop -- using layers -- would work too). I used the bitmap image (Important: the bitmap image needs to be at 100% of the final art size) as a guide to place my color and create areas where there would be no color. I also tossed in a background drawn in Freehand from an earlier test of this Modern Coloring Technique (see image above right). I then printed out the result on a sheet of 2-ply bristol board.
Next I placed the color printout on top of a printout of the bitmap image and placed them on a lightbox. I then lightly penciled in any necessary details. (Alternate tracing method: take the two sheets and tape them on a window backlit by bright sunlight.) Your art is now ready to be inked so ink away. The final art, done for my pal Dan, can be seen below.

I don't recommend this technique for creating work that is intended to be reproduced. But if you are, say, a comic book or strip artist who wants to create inexpensive original color art for your fans at conventions or via eBay this sort of thing might work for you.
Here are a couple of other original pieces I did using this gimmick (click on the art for larger images).

