Enable cheats and enter one of the following codes to affect Sarge:

Drop Sarge's health to almost 0 = !let me down

Large explosion around Sarge = !italian job

Sarge has a flak-jacket = !whistle and flute

Sarge has a force field = !stay frosty

Sarge is on fire but doesn't take damage = !disco inferno

Extinguish Sarge = !disco is dead