This is NOT a simple mod..
basicly i would say that you could only use the rest of the player case.
you need a data cdrom drive, microcontroller system with some video and audio decoder...
What dows these kits include? you need a lot of electronics
to "convert" a audio player to VCD player.
the audio player contains no "processor" that can handle compressed audio or video, it almost directly streams the data from the cd through the dac. (or to digital output)
wheras vcd's need decompression of the mpeg1 stream!.