1. Contact Borderlands Books (http://borderlands-books.com/) in San Francisco, California. You can contact them by either email or phone; check the website for specific options.
2. Order books! You have to tell them which ones, naturally, and whether you want them signed and personalized, or just signed. Personalized books must be paid for up-front. You can request a specific inscription. Some inscriptions (ie, my phone number) will be refused, although your book will still be signed.
3. While you're at it, order anything else that you'd like to get. I mean, hello, bookstore, and you're already paying for shipping, so why the heck not?
4. Give the store any information they need, like shipping address and billing and stuff.
5. The store will contact me, and I'll go in and sign things!
If you want your book or books shipped in time for Christmas, you need to contact the store and place your order by December 12th. That's still not a guarantee, especially if you're in like, England, but at least it's a ballpark.
But wait, you cry! What books are currently available?
TOBY: Rosemary and Rue, A Local Habitation, An Artificial Night, Late Eclipses, One Salt Sea, and Ashes of Honor.
INCRYPTID: Discount Armageddon.
NEWSFLESH: Feed, Deadline, Blackout, and the Newsflesh box set.
VELVETEEN: Velveteen vs. The Junior Super Patriots.
ANTHOLOGIES: The Living Dead 2 (Newsflesh-universe story); Home Improvement: Undead Edition (Toby-universe story); Zombiesque; Westward Weird (Incryptid-universe story); Tales From the Ur-Bar; Human For a Day; The Modern Fae's Guide to Surviving Humanity; Other Worlds Than These; Human Tales; Grants Pass.
Because Borderlands does not carry non-fiction, none of the Mad Norwegian Press titles are available from them.
(Post concept gleefully stolen from John Scalzi. I love you, John!)