Clip out a section of 128x32 pixels and dither it down to the four colors that the empeg screen has under typical driving conditions, black, almost black, a bit less black, and visible. If that is really what you want to use for navigation, nobody is stopping you.

One thing you would need is to georeference the images, i.e. find the precise coordinates of the bitmap corners and build a transformation function that can map the GPS position to a map location. Oh, and this has to be done for every single image and will only be useful for the handful or people in the UK that actually buy those CD's and would sit down and do the print screen/georeferencing for every part they are interested in.

You could try to figure out what that proprietary format is, maybe it is (or contains) a standard geotiff file.