Given your requirements, the only option I see is dying by way of hanging (Partial or otherwise).
You will need a strong rope to support your weight and a strong anchor (doorknob with the rope thrown over the top of the door, some kind of beam above your head, or even a tree branch.) Remember that the knot goes BEHIND your neck, high and in front of the face. Position the rope so that it will tighten around the neck, with emphasis on applying pressure to the carotid artery. Now, apply pressure by either kneeling, lying down, or some sort of variation you are comfortable with. The pressure you feel around your neck will restrict blood flow into the brain, causing you to lose consciousness fairly quickly.
Even if you are unconscious, SI will undoubtedly kick in; your body will begin to thrash around, trying desperately to survive. This is why it is important to test the strength of your rope, the security of your knot , as well as the strength of your beam before you attempt this.
