Load up chapter 1-1 on Veteran difficulty and get to the first wave of enemies that spawn. Make sure Sheva has no weapons or herbs and lead the enemies to her. Once she gets hurt and the "Dying" is displayed on her HUD run over and resuscitate her. I'd suggest keeping a few green herbs handy if you want. On Professional difficulty it's a one hit kill to be put in a "Dying" state, but will take less time. You must complete the game on Veteran difficulty to unlock Professional