[B] activates comm panel then type CISCO SEZ then hit [enter].
After that you can put in these codes after you press [B]:

Code Result 
BE MY BUDDY Targeted ship or sub will become ally. 
FLIP HER Turns sub around. 
ZEPPLIN Sub flys like a blimp. 
DROP ANCHOR Makes sub stop. 
HEAL ME Fixes sub. 
EAT LEAD Changes torpedo. 
BOOM Targeted object will explode. 
SEE THEM Improves sonar. 
ENGAGE CLOAKING DEVICE Hides sub from enemy sonar.