I strongly recommend before you start with a date in mind that you step back and get a solid study book to work through. Both the Todd Lammle's guide and the Cisco Press book are recommended. I personally used the Cisco Press book which comes with an excellent set of practice questions.
To answer your question about IPv6 in particular, let me point you to the things you're going to want to learn about. Between Wikipedia, Cisco's whitepapers, and some googlefu you should be able getting the info you need.
IPv6 address format, EUI-64, reserved prefixes (like FF00::/8), zero compression, differences between IPv6 and IPv4 headers, network discovery protocol, static/dynamic address assignment, stateful and stateless DHCPv6 servers, general IPv6 commands (enabling it on a router and specific interfaces), IPv6 routing protocols (names and basic configuration), dual stack, tunneling, manually configured tunnels, dynamic 6to4, ISATAP, Teredo tunneling, and NAT-PT.