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

POKE 13205,X
SYS 2304 
Level select:
Load or reset the game, then execute the following BASIC commands before running or restarting the program. Note: X represents the desired starting level. 

POKE 13206,X
SYS 2304 
Unlimited lives:
Load or reset the game, then execute the following BASIC commands before running or restarting the program. 

POKE 3022,234
POKE 3023,234
POKE 3028,234
SYS 2304 
Unlimited lives (alternate):
Load or reset the game, then execute the following BASIC commands before running or restarting the program. 

POKE 3029,234
SYS 2304 
Unlimited lives (alternate):
Load or reset the game, then execute the following BASIC commands before running or restarting the program. 

POKE 3400,255
POKE 3406,255 
Invincibility:
Load or reset the game, then execute the following BASIC command before running or restarting the program. 

POKE 3394,255