Enter these like normal.
Result: --- Password:
Start game at level 1 --- Vein, Heart, Bottle, Head, Bone, Boln, Bone, Syringe, Head, Bottle, Portal, Bottle, Bone, Syringe, Bottle
Start game at level 2 --- Chase, Syringe, Heart, Bottle, Head
Note: This will not work on early model Sega CD units. Open the CD lid when the Boss appears to prevent it from moving. Destroy the Boss, close the CD lid, and continue game play.