Invincibility:
Repeatedly type RED at the title screen until the word "Red" appears. 

Cheat mode:
Load or reset the game, then execute the following BASIC command before running or restarting the program. 

POKE 34488,173 
Set number of lives:
Load or reset the game, then execute the following BASIC command before running or restarting the program. Note: X represents the desired number of lives. 

POKE 11353,X