You can do it manually, just add a 4 spheres to the scene, select one, then I think it was ctrl + shift + C on either the bones of the hands or feet, then go to bone constraints and set the chain length to 3.
- Anything is Possible -
If anybody here knows how to do script mods, and you want to help me with a special mod I'll be doing for Sims 3 (hopefully), please PM me, and I'll give you details and how you will be credited. Take your time if you do plan on helping me. Thank you.