Go to your "Settings" page in your 22Slides control panel and click the "Set Up a Custom Domain" button in the "Domain Name" section.
Enter your domain name in the blank and click the "Setup Custom Domain" button.
Login to Hover.com and click on your domain.
Click the "Connect" tab.
Find 22Slides in the list and click "Get Started".
That's it, you're done! Your domain should start working within an hour or two, however it's recommended to wait about 12 hours before sharing your site with others, since different parts of the world might take a bit longer to see the changes you just made.