Don't blow through all their boxes and overflow?
Shadowrun has a plethora of non-lethal options, including the Social skills like Intimidation. If the GM says the Titanium bars in your bones are always going to be Lethal damage, use something else. Or Grapple them, should be about the same dice pools.
Despite what you see in movies and TV, hitting someone in the head with a monkey wrench or frying pan can easily be fatal. That fine line between concussed and unconscious and subdural hematoma is a tough one to judge.
Also, Med-kit, Trauma Patch, Healing Magic, and First Aid Skill for if you do cross that line and need someone to talk to after the dust settles.
But mostly just talk to your GM.