Pinouts for the Odyssey2 joystick port:
 ___________
( 1 2 3 4 5 )
 \ 6 7 8 9 /
  \_______/

1 - Ground
2 - Fire
3 - Left
4 - Down
5 - Right
6 - Up
7,8,9 - not connected
 

Pinouts for the Atari 2600 (etc) port, just for reference:
 ___________
( 1 2 3 4 5 )
 \ 6 7 8 9 /
  \_______/

1 - Up
2 - Down
3 - Left
4 - Right
6 - Fire
8 - Ground
5,7,9 - not connected (actually, paddle inputs, etc)