Here's the colored version; please check out the black & white line art in the gallery.
I scan the art into my computer with an Epson Expression 836XL oversized scanner. I then clean up the scan in Photoshop.
I convert the file to CMYK Mode, with the lineart as a 5th Channel, visible but not active. The CMYK Channel is white, so that the practical effect is coloring on a black white area, with the art 'floating' above it. Visible, but unaltered unless I shoose to do so.