programming C+ > reverse engineer/write a palm program

a) we have an old palm program from a defunct company that we would like to 1) decompile and recreate, or 2) recreate from scratch. the program has a very narrow use to read code from an old c2002 automobile OBD computer to the palm screen. We also want to update the program from the m515 OS to the Tungsten OS. b) we also want the program available for further mods (additional data to screen) and want to get it working on a prototype vehicle we have. see pictures.