All you should have to do is call VZW Customer service, establish an account, or use an existing account and give them the information printed on the back of the phone under the battery.
I would call VZW first with the info before you buy it to make sure it's not reported as stolen. But, you can bring your own CDMA equipment to VZW reguardless. It does not have to be approved by VZW or sold by VZW.
I've done this with a bunch of phones.
Hope this helps.