I had to give the Hackvision software a crack, and I got it working on
my Arduino:
http://tinypic.com/r/2yxi62h/7
It looks pretty neat on the TV. The underlying library is actually
fairly well written - with the code that handles the low level stuff
(sync, turning colour on and off etc) separate from the bit that draws
lines and characters - so you could use it to generate sync pulses
while you could take control of the drawing yourself during the frame
and make patterns.
I got these Arduino connections from the schematic:
9: Vsync (see
http://code.google.com/p/arduino-tvout/)
7: Video
12: gnd (for PAL, leave disconnected for NTSC)
3: left button
2: right button
4: up button
5: down button
10: fire button
(all buttons go to gnd)