When you first get Han Solo (he's inside the Cantina in the Mos Eisley level), immediately switch over to him and allow him to die. You should restart as Luke in the spot where you first found Han. Now exit and re-enter the Cantina. Make your way back to where Han was and you will obtain him again. This time however, Han's health bar will start completely depleted and you will not die from normal enemy or environmental attacks. Note- The Invincible Han effect will be removed if you: 1.) Pick up a health pack with him 2.) Use Obi Wan to resurrect him or Leia 3.) Suffer fall damage.