This seems similar to the Dreamcast situation. You can set H.Samplerate to 800 and H.Active to 640 for a 4:3 VGA output, possibly your TV will detect this properly without trying to stretch it. Easiest way to do this is to change 480p sampling options from DTV to VGA. However this will undersample the image so you will lose some horizontal details and possibly get aliasing artifacts. So it is not ideal.