I just did this. Once you get your VPS server setup with WHM. Just log into whm and use account transfer. It will do all the work for you. I transfered 15 accounts with no problem. Everything works like it did on the old server.
cPanel/WHM is a single product. When you purchase a VPS license of cPanel/WHM, you get both cPanel and WHM. VPS licenses of cPanel/WHM offer the same functionality as their dedicated server counterparts. However, VPS licenses can only be used in VPS environments. They cannot be used in dedicated server environments.