I've read I would need to replace the SIM card with local China carrier. However, I need to have the
card slot "unlocked". How do I do this?
Are you currently a Verizon customer (in good standing etc)? If so, you can call them up, ask for Global Services, and ask them to unlock the SIM slot. You may need to explain that you want to use it abroad, as "unlock" has too many different meanings.