Can you make your own ragdoll?

I used Unity's Ragdoll wizard to create ragdolls for my characters. The created colliders will also function as hit boxes for player attacks. But I'd like more colliders for other parts of the body than the default ones that Unity's Ragdoll adds (such as shoulders, feet, hands, etc.)

Is Unity's Ragdoll wizard an actual system doing more under the hood, or is it just a quick way to add those 12 different colliders and joints on a rig? Can I just create colliders for bones on my own and disable IsKinematic when ragdoll is needed and that will work just the same?