The Shadowlands is a private Minecraft server run by GeoffTheGreat and SleepSeeker.
To join Shadowlands, send SleepSeeker an email.
Let him know who you are, and give him your Minecraft character's name, spelled exactly as it is in-game.
REMINDER: Do not share your Minecraft password with SleepSeeker - never share your password with anyone.
SleepSeeker will respond with instructions on how to connect to the server, including information on the server's IP address and port number.
Creating a 1.6.4 Profile
While you are waiting for a response from SleepSeeker, you can create a Minecraft profile for 1.6.4, following these instructions.
To create a new 1.6.4 profile, launch Minecraft and press the New Profile button in the bottom-left of the window.
This will open a new window; configure your new profile as follows:
You can name your profile whatever you want - GeoffTheGreat named his GeoffTheGreat 1.6.4 so he knew the version the server is running.