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.
To all the readers of my little experiment in self-therapy, I hope you all have a very Merry Christmas!