I spent a little while trying to figure this out, apparently the -r argument is significant:

ffmpeg -i superman_the_mechanical_monsters.mpeg \
    -title "Superman: The Mechanical Monsters" \ 
     -s 320x240 -b 512 -ar 24000 -ab 64 -r 29.970030 -f psp M4V12345.MP4

The -title seemed fubarred, but the rest seems to work. I’ll refine this more later.

Filenames apparently need to be of the form M4VXXXXX.MP4, where the X’s are digits.