UCM3 models use standard 24-bit Windows BMP images to store the
data for each individual page or part. The BMP format stores its
image data in red, green, and blue channels, and UCM3 model data
is encoded into these BMP images as follows:

Red channel: Texture
Green Channel: Region index
Blue Channel: Lines, tabs, and text

This is why the BMPs belonging to UCM3 models look so strange.

In order to edit them, you have a few options. If you just want
to rearrange parts, you can simply open the BMPs and do things
like cutting and pasting the parts. Just keep in mind that if
you do cut and paste the parts-the background of the new image
into which you paste the parts MUST be blue (RGB 0,0,255), as
that will translate into the standard white paper color.

If you want to rearrange, add, or delete regions, you'll need
to first split the BMPs into individual channels. In Paint Shop
Pro, for instance, this can be done by using the Split Channel>
Split To RGB function under the Colors menu. You'll end up with
three images...a grayscale texture map, a grayscale region map
(which may appear black, but isn't really black), and a third
image consisting of black lines and text on a white background.

The region map bears some additional commentary...this image is
where all of the region data is stored. Pixels that are pure
black (RGB 0,0,0) correspond to the paper color, and all other
pixel values from RGB 1,1,1 to RGB 255,255,255 directly map to
the editable regions. You may want to convert the region map to
full color and then flood fill with random colors to see each 
region better. Make sure that you restore the regions to their
appropriate grayscale values before recombining the separate
channels into a single image.