Unlimited lives:
Load or reset the game, then execute the following BASIC commands before running or restarting the program. 

POKE 47378,165
SYS 49125 

Unlimited lives (alternate):
Load or reset the game, then execute the following BASIC command before running or restarting the program. 

POKE 25088,250 

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

POKE 23114,255